1
|
Mpakali A, Barla I, Lu L, Ramesh KM, Thomaidis N, Stern LJ, Giastas P, Stratikos E. Mechanisms of Allosteric Inhibition of Insulin-Regulated Aminopeptidase. J Mol Biol 2024; 436:168449. [PMID: 38244767 DOI: 10.1016/j.jmb.2024.168449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 01/12/2024] [Accepted: 01/14/2024] [Indexed: 01/22/2024]
Abstract
Inhibition of Insulin-Regulated Aminopeptidase is being actively explored for the treatment of several human diseases and several classes of inhibitors have been developed although no clinical applications have been reported yet. Here, we combine enzymological analysis with x-ray crystallography to investigate the mechanism employed by two of the most studied inhibitors of IRAP, an aryl sulfonamide and a 2-amino-4H-benzopyran named HFI-419. Although both compounds have been hypothesized to target the enzyme's active site by competitive mechanisms, we discovered that they instead target previously unidentified proximal allosteric sites and utilize non-competitive inhibition mechanisms. X-ray crystallographic analysis demonstrated that the aryl sulfonamide stabilizes the closed, more active, conformation of the enzyme whereas HFI-419 locks the enzyme in a semi-open, and likely less active, conformation. HFI-419 potency is substrate-dependent and fails to effectively block the degradation of the physiological substrate cyclic peptide oxytocin. Our findings demonstrate alternative mechanisms for inhibiting IRAP through allosteric sites and conformational restricting and suggest that the pharmacology of HFI-419 may be more complicated than initially considered. Such conformation-specific interactions between IRAP and small molecules can be exploited for the design of more effective second-generation allosteric inhibitors.
Collapse
Affiliation(s)
- Anastasia Mpakali
- Laboratory of Biochemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens 15771, Greece; National Centre for Scientific Research Demokritos, Athens 15341, Greece
| | - Ioanna Barla
- Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens 15771, Greece
| | - Liying Lu
- Department of Pathology, UMass Chan Medical School, Worcester, MA 01650, USA
| | - Karthik M Ramesh
- Department of Pathology, UMass Chan Medical School, Worcester, MA 01650, USA
| | - Nikolaos Thomaidis
- Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens 15771, Greece
| | - Lawrence J Stern
- Department of Pathology, UMass Chan Medical School, Worcester, MA 01650, USA
| | - Petros Giastas
- Department of Biotechnology, School of Applied Biology & Biotechnology, Agricultural University of Athens, Athens 11855, Greece
| | - Efstratios Stratikos
- Laboratory of Biochemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens 15771, Greece; National Centre for Scientific Research Demokritos, Athens 15341, Greece.
| |
Collapse
|
2
|
Telianidis J, Hunter A, Widdop R, Kemp-Harper B, Pham V, McCarthy C, Chai SY. Inhibition of insulin-regulated aminopeptidase confers neuroprotection in a conscious model of ischemic stroke. Sci Rep 2023; 13:19722. [PMID: 37957163 PMCID: PMC10643421 DOI: 10.1038/s41598-023-46072-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 10/27/2023] [Indexed: 11/15/2023] Open
Abstract
Stroke is a leading cause of mortality and morbidity with a paucity of effective pharmacological treatments. We have previously identified insulin-regulated aminopeptidase (IRAP) as a potential target for the development of a new class of drugs for the treatment of stroke, as global deletion of this gene in mice significantly protected against ischemic damage. In the current study, we demonstrate that small molecular weight IRAP inhibitors reduce infarct volume and improve neurological outcome in a hypertensive animal model of ischemic stroke. The effects of two structurally distinct IRAP inhibitors (HFI419 or SJM164) were investigated in a model of stroke where the middle cerebral artery was transiently occluded with endothelin-1 in the conscious spontaneously hypertensive rat. IRAP inhibitor was administered into the lateral ventricle at 2 or 6 h after stroke, with subsequent doses delivered at 24, 48 and 70 h post-stroke. Functional outcomes were assessed prior to drug treatment, and on day 1 and 3 post-stroke. Histological analyses and neuroinflammatory cytokine profiling were conducted at 72 and 24 h post-stroke respectively. IRAP inhibitor treatment following stroke significantly reduced infarct volume and improved neurological and motor deficits. These protective effects were maintained even when the therapeutic window was extended to 6 h. Examination of the cellular architecture at 72 h post-stroke demonstrated that IRAP expression was upregulated in CD11b positive cells and activated astrocytes. Furthermore, IRAP inhibitor treatment significantly increased gene expression for interleukin 6 and C-C motif chemokine ligand 2 in the ischemic core. This study provides proof-of-principle that selective inhibition of IRAP activity with two structurally distinct IRAP inhibitors reduces infarct volume and improves functional outcome even when the first dose is administered 6 h post-stroke. This is the first direct evidence that IRAP inhibitors are a class of drug with potential use in the treatment of ischemic stroke.
Collapse
Affiliation(s)
- Jonathon Telianidis
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Andrew Hunter
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Robert Widdop
- Department Pharmacology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Barbara Kemp-Harper
- Department Pharmacology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Vi Pham
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Claudia McCarthy
- Department Pharmacology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Siew Yeen Chai
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia.
| |
Collapse
|
3
|
Engen K, Vanga SR, Lundbäck T, Agalo F, Konda V, Jensen AJ, Åqvist J, Gutiérrez-de-Terán H, Hallberg M, Larhed M, Rosenström U. Synthesis, Evaluation and Proposed Binding Pose of Substituted Spiro-Oxindole Dihydroquinazolinones as IRAP Inhibitors. ChemistryOpen 2020; 9:325-337. [PMID: 32154052 PMCID: PMC7050655 DOI: 10.1002/open.201900344] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 01/23/2020] [Indexed: 12/13/2022] Open
Abstract
Insulin-regulated aminopeptidase (IRAP) is a new potential macromolecular target for drugs aimed for treatment of cognitive disorders. Inhibition of IRAP by angiotensin IV (Ang IV) improves the memory and learning in rats. The majority of the known IRAP inhibitors are peptidic in character and suffer from poor pharmacokinetic properties. Herein, we present a series of small non-peptide IRAP inhibitors derived from a spiro-oxindole dihydroquinazolinone screening hit (pIC50 5.8). The compounds were synthesized either by a simple microwave (MW)-promoted three-component reaction, or by a two-step one-pot procedure. For decoration of the oxindole ring system, rapid MW-assisted Suzuki-Miyaura cross-couplings (1 min) were performed. A small improvement of potency (pIC50 6.6 for the most potent compound) and an increased solubility could be achieved. As deduced from computational modelling and MD simulations it is proposed that the S-configuration of the spiro-oxindole dihydroquinazolinones accounts for the inhibition of IRAP.
Collapse
Affiliation(s)
- Karin Engen
- Department of Medicinal Chemistry Uppsala University SE-751 23 Uppsala SWEDEN
| | - Sudarsana Reddy Vanga
- Department of Cell and Molecular Biology Uppsala University SE-751 23 Uppsala SWEDEN
| | - Thomas Lundbäck
- Chemical Biology Consortium Sweden, Science for Life Laboratory, Department of Medical Biochemistry and Biophysics Karolinska Institutet SE-171 65 Solna SWEDEN
- Mechanistic Biology & Profiling, Discovery Sciences, R&D AstraZeneca SE-431 83 Göteborg SWEDEN
| | - Faith Agalo
- Department of Medicinal Chemistry Uppsala University SE-751 23 Uppsala SWEDEN
| | - Vivek Konda
- Department of Medicinal Chemistry Uppsala University SE-751 23 Uppsala SWEDEN
| | - Annika Jenmalm Jensen
- Chemical Biology Consortium Sweden, Science for Life Laboratory, Department of Medical Biochemistry and Biophysics Karolinska Institutet SE-171 65 Solna SWEDEN
| | - Johan Åqvist
- Department of Cell and Molecular Biology Uppsala University SE-751 23 Uppsala SWEDEN
| | - Hugo Gutiérrez-de-Terán
- Science for Life Laboratory, Department of Cell and Molecular Biology Uppsala University SE-751 23 Uppsala SWEDEN
| | - Mathias Hallberg
- The Beijer Laboratory, Department of Pharmaceutical Biosciences Uppsala University SE-751 23 Uppsala SWEDEN
| | - Mats Larhed
- Science for Life Laboratory, Department of Medicinal Chemistry Uppsala University SE-751 23 Uppsala SWEDEN
| | - Ulrika Rosenström
- Department of Medicinal Chemistry Uppsala University SE-751 23 Uppsala SWEDEN
| |
Collapse
|
4
|
Albiston AL, Cacador M, Sinnayah P, Burns P, Chai SY. Insulin-regulated aminopeptidase inhibitors do not alter glucose handling in normal and diabetic rats. J Mol Endocrinol 2017; 58:193-198. [PMID: 28356324 DOI: 10.1530/jme-17-0033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 03/29/2017] [Indexed: 11/08/2022]
Abstract
Insulin-regulated aminopeptidase (IRAP) co-localizes with the glucose transporter 4 (GLUT4) in GLUT4 storage vesicles (GSV) in insulin-responsive cells. In response to insulin, IRAP is the only transmembrane enzyme known to translocate together with GLUT4 to the plasma membrane in adipocytes and muscle cells. Although the intracellular region of IRAP is associated with GLUT4 vesicle trafficking, the role of the aminopeptidase activity in insulin-responsive cells has not been elucidated. The aim of this study was to investigate whether the inhibition of the aminopeptidase activity of IRAP facilitates glucose uptake in insulin-responsive cells. In both in vitro and in vivo studies, inhibition of IRAP aminopeptidase activity with the specific inhibitor, HFI-419, did not modulate glucose uptake. IRAP inhibition in the L6GLUT4myc cell line did not alter glucose uptake in both basal and insulin-stimulated state. In keeping with these results, HFI419 did not affect peripheral, whole-body glucose handling after an oral glucose challenge, neither in normal rats nor in the streptozotocin (STZ)-induced experimental rat model of diabetes mellitus (DM). Therefore, acute inhibition of IRAP aminopeptidase activity does not affect glucose homeostasis.
Collapse
Affiliation(s)
- Anthony L Albiston
- College of Health and BiomedicineVictoria University St Albans, Victoria, Australia
| | - Mauricio Cacador
- College of Health and BiomedicineVictoria University St Albans, Victoria, Australia
| | - Puspha Sinnayah
- College of Health and BiomedicineVictoria University St Albans, Victoria, Australia
| | - Peta Burns
- Department of PhysiologyBiomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Siew Yeen Chai
- Department of PhysiologyBiomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| |
Collapse
|
5
|
Modi ME, Young LJ. The oxytocin system in drug discovery for autism: animal models and novel therapeutic strategies. Horm Behav 2012; 61:340-50. [PMID: 22206823 PMCID: PMC3483080 DOI: 10.1016/j.yhbeh.2011.12.010] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 12/12/2011] [Accepted: 12/13/2011] [Indexed: 01/13/2023]
Abstract
Animal models and behavioral paradigms are critical for elucidating the neural mechanism involved in complex behaviors, including social cognition. Both genotype and phenotype based models have implicated the neuropeptide oxytocin (OT) in the regulation of social behavior. Based on the findings in animal models, alteration of the OT system has been hypothesized to play a role in the social deficits associated with autism and other neuropsychiatric disorders. While the evidence linking the peptide to the etiology of the disorder is not yet conclusive, evidence from multiple animal models suggest modulation of the OT system may be a viable strategy for the pharmacological treatment of social deficits. In this review, we will discuss how animal models have been utilized to understand the role of OT in social cognition and how those findings can be applied to the conceptualization and treatment of the social impairments in ASD. Animal models with genetic alterations of the OT system, like the OT, OT receptor and CD38 knock-out mice, and those with phenotypic variation in social behavior, like BTBR inbred mice and prairie voles, coupled with behavioral paradigms with face and construct validity may prove to have predictive validity for identifying the most efficacious methods of stimulating the OT system to enhance social cognition in humans. The widespread use of strong animal models of social cognition has the potential yield pharmacological, interventions for the treatment social impairments psychiatric disorders. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.
Collapse
Affiliation(s)
| | - Larry J. Young
- Corresponding author. 954 Gatewood Road, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA. (L.J. Young)
| |
Collapse
|
6
|
Demaegdt H, Lukaszuk A, De Buyser E, De Backer JP, Szemenyei E, Tóth G, Chakravarthy S, Panicker M, Michotte Y, Tourwé D, Vauquelin G. Selective labeling of IRAP by the tritiated AT(4) receptor ligand [3H]Angiotensin IV and its stable analog [3H]AL-11. Mol Cell Endocrinol 2009; 311:77-86. [PMID: 19643163 DOI: 10.1016/j.mce.2009.07.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 07/14/2009] [Accepted: 07/21/2009] [Indexed: 11/22/2022]
Abstract
'AT(4) receptors' through which Angiotensin IV (Ang IV) improves memory acquisition, were recently identified as insulin regulated aminopeptidase (IRAP). Radioligand binding studies have hitherto been performed with iodinated Ang IV in the presence of divalent cation chelators EDTA and 1,10-phenanthrolin. Hence, they referred to the apo-form of IRAP. Presently, binding of [(3)H]Ang IV and [(3)H]AL-11, a stable Ang IV analog, was compared on Chinese hamster ovary (CHO-K1) and mouse hippocampal (P40H1) cell membranes. With chelators, their high affinity sites showed the same pharmacological profile as for [(125)I]Ang IV binding. Without chelators, only high affinity binding was perceived for [(3)H]AL-11. The same pharmacological profile was recorded in both membrane preparations; it was different from the one in the presence of chelators and corresponded to catalytically active IRAP (despite the concurrent presence of aminopeptidase N (APN) in P40H1 cell membranes). This confirms that the active and apo-forms of IRAP have a distinct pharmacological profile.
Collapse
Affiliation(s)
- Heidi Demaegdt
- Research Group of Experimental Pharmacology, Department of Molecular and Biochemical Pharmacology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Chai SY, Yeatman HR, Parker MW, Ascher DB, Thompson PE, Mulvey HT, Albiston AL. Development of cognitive enhancers based on inhibition of insulin-regulated aminopeptidase. BMC Neurosci 2008; 9 Suppl 2:S14. [PMID: 19090987 PMCID: PMC2604898 DOI: 10.1186/1471-2202-9-s2-s14] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The peptides angiotensin IV and LVV-hemorphin 7 were found to enhance memory in a number of memory tasks and reverse the performance deficits in animals with experimentally induced memory loss. These peptides bound specifically to the enzyme insulin-regulated aminopeptidase (IRAP), which is proposed to be the site in the brain that mediates the memory effects of these peptides. However, the mechanism of action is still unknown but may involve inhibition of the aminopeptidase activity of IRAP, since both angiotensin IV and LVV-hemorphin 7 are competitive inhibitors of the enzyme. IRAP also has another functional domain that is thought to regulate the trafficking of the insulin-responsive glucose transporter GLUT4, thereby influencing glucose uptake into cells. Although the exact mechanism by which the peptides enhance memory is yet to be elucidated, IRAP still represents a promising target for the development of a new class of cognitive enhancing agents.
Collapse
Affiliation(s)
- Siew Yeen Chai
- Howard Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
- Centre for Neuroscience, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Holly R Yeatman
- Howard Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
- Centre for Neuroscience, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Michael W Parker
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
- St Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - David B Ascher
- St Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - Philip E Thompson
- Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Hayley T Mulvey
- Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Anthony L Albiston
- Howard Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| |
Collapse
|
8
|
Albiston AL, Peck GR, Yeatman HR, Fernando R, Ye S, Chai SY. Therapeutic targeting of insulin-regulated aminopeptidase: heads and tails? Pharmacol Ther 2007; 116:417-27. [PMID: 17900701 DOI: 10.1016/j.pharmthera.2007.07.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 07/30/2007] [Indexed: 10/22/2022]
Abstract
Insulin-regulated aminopeptidase, IRAP, is an abundant protein that was initially cloned from a rat epididymal fat pad cDNA library as a marker protein for specialized vesicles containing the insulin-responsive glucose transporter GLUT4, wherein it is thought to participate in the tethering and trafficking of GLUT4 vesicles. The same protein was independently cloned from human placental cDNA library as oxytocinase and is proposed to have a primary role in the regulation of circulating oxytocin (OXY) during the later stages of pregnancy. More recently, IRAP was identified as the specific binding site for angiotensin IV, and we propose that it mediates the memory-enhancing effects of the peptide. This protein appears to have multiple physiological roles that are tissue- and domain-specific; thus the protein can be specifically targeted for treating different clinical conditions.
Collapse
Affiliation(s)
- Anthony L Albiston
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria 3010, Australia
| | | | | | | | | | | |
Collapse
|
9
|
Stragier B, Demaegdt H, De Bundel D, Smolders I, Sarre S, Vauquelin G, Ebinger G, Michotte Y, Vanderheyden P. Involvement of insulin-regulated aminopeptidase and/or aminopeptidase N in the angiotensin IV-induced effect on dopamine release in the striatum of the rat. Brain Res 2007; 1131:97-105. [PMID: 17169335 DOI: 10.1016/j.brainres.2006.11.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Revised: 10/20/2006] [Accepted: 11/05/2006] [Indexed: 11/21/2022]
Abstract
Locally administered angiotensin IV causes a dose-dependent increase of the dopamine levels in the striatum of the rat. The aminopeptidases insulin-regulated aminopeptidase (IRAP) and/or aminopeptidase N (AP-N) are proposed to be involved in this effect since both enzymes are inhibited by angiotensin IV. In agreement with this hypothesis we demonstrate that by using the AP-N selective inhibitor 7B, about 60% of the aminopeptidase activity in striatal membranes could be attributed to AP-N (pK(i)=9.20). Higher concentrations of 7B are capable of inhibiting IRAP as well (pK(i)=7.26). Interestingly, in vivo, inhibition of IRAP or AP-N activity does not appear to be involved in the angiotensin IV-mediated effect in the striatum since 7B itself is not capable to induce dopamine release such as observed with angiotensin IV. However, 7B at a concentration selective for inhibition of AP-N (100 nM) potentiates the angiotensin IV-mediated increase of dopamine, suggesting that inhibition of AP-N lengthens the half-life of angiotensin IV. On the other hand, inhibition of both AP-N and IRAP by perfusion of 500 nM 7B completely abolishes the effect of angiotensin IV. We therefore hypothesize that the effect of angiotensin IV on dopamine release in the striatum is mediated via activation of IRAP and/or AP-N, possibly acting as receptors for angiotensin IV.
Collapse
Affiliation(s)
- Bart Stragier
- Research Group Experimental Pharmacology, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Vrije Universiteit Brussel Laarbeeklaan 103 B-1090 Brussels, Belgium
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Ye S, Chai SY, Lew RA, Albiston AL. Insulin-regulated aminopeptidase: analysis of peptide substrate and inhibitor binding to the catalytic domain. Biol Chem 2007; 388:399-403. [PMID: 17391061 DOI: 10.1515/bc.2007.044] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Peptide inhibitors of insulin-regulated aminopeptidase (IRAP) accelerate spatial learning and facilitate memory retention and retrieval by binding competitively to the catalytic site of the enzyme and inhibiting its catalytic activity. IRAP belongs to the M1 family of Zn2+-dependent aminopeptidases characterized by a catalytic domain that contains two conserved motifs, the HEXXH(X)18E Zn2+-binding motif and the GXMEN exopeptidase motif. To elucidate the role of GXMEN in binding peptide substrates and competitive inhibitors, site-directed mutagenesis was performed on the motif. Non-conserved mutations of residues G428, A429 and N432 resulted in mutant enzymes with altered catalytic activity, as well as divergent changes in kinetic properties towards the synthetic substrate leucine beta-naphthylamide. The affinities of the IRAP inhibitors angiotensin IV, Nle1-angiotensin IV, and LVV-hemorphin-7 were selectively decreased. Substrate degradation studies using the in vitro substrates vasopressin and Leu-enkephalin showed that replacement of G428 by either D, E or Q selectively abolished the catalysis of Leu-enkephalin, while [A429G]IRAP and [N432A]IRAP mutants were incapable of cleaving both substrates. These mutational studies indicate that G428, A429 and N432 are important for binding of both peptide substrates and inhibitors, and confirm previous results demonstrating that peptide IRAP inhibitors competitively bind to its catalytic site.
Collapse
Affiliation(s)
- Siying Ye
- Howard Florey Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | | | | | | |
Collapse
|
11
|
Demaegdt H, Lenaerts PJ, Swales J, De Backer JP, Laeremans H, Le MT, Kersemans K, Vogel LK, Michotte Y, Vanderheyden P, Vauquelin G. Angiotensin AT4 receptor ligand interaction with cystinyl aminopeptidase and aminopeptidase N: [125I]Angiotensin IV only binds to the cystinyl aminopeptidase apo-enzyme. Eur J Pharmacol 2006; 546:19-27. [PMID: 16919623 DOI: 10.1016/j.ejphar.2006.07.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Revised: 06/07/2006] [Accepted: 07/13/2006] [Indexed: 10/24/2022]
Abstract
Due to its high affinity for [(125)I]Angiotensin IV, cystinyl aminopeptidase (CAP) has recently been assigned as the 'angiotensin AT(4) receptor'. Since the aminopeptidase N (AP-N) activity is also susceptible to inhibition by Angiotensin IV, it might represent an additional target for this peptide. Based on [(125)I]Angiotensin IV binding and catalytic activity measurements, we compared the ligand interaction properties of recombinant human CAP and human AP-N. Both enzymes displayed distinct pharmacological profiles. Although their activity is inhibited by Angiotensin IV and LVV-hemorphin 7, both peptides are more potent CAP-inhibitors. On the other hand, substance P and l-methionine have a higher potency for AP-N. High affinity binding of [(125)I]Angiotensin IV to CAP occurs in the presence of chelators but not to AP-N in either the absence or presence of chelators. These differences were exploited to determine whether CAP and/or AP-N are present in different cell lines (CHO-K1, COS-7, HEK293, SK-N-MC and MDBK). We provide evidence that CAP predominates in these cell lines and that, comparatively, CHO-K1 cells display the highest level of this enzyme.
Collapse
Affiliation(s)
- Heidi Demaegdt
- Research Group on Experimental Pharmacology, Department of Molecular and Biochemical Pharmacology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Abstract
The angiotensin IV receptor (AT4 receptor) is the insulin-regulated aminopeptidase enzyme (IRAP, EC 3.4.11.3). This membrane-spanning enzyme belongs to the M1 family of zinc-dependent metallo-peptidases. It has been proposed that AT4 receptor ligands exert their physiological effects by binding to the active site of IRAP and thereby inhibiting the catalytic activity of the enzyme. The biological activity of a large series of linear angiotensin IV analogs was previously disclosed. Herein, the synthesis and biological evaluation of a series of angiotensin IV analogs, encompassing macrocyclic ring systems of different sizes, are presented. It is demonstrated that disulfide cyclizations of angiotensin IV can deliver ligands with high IRAP/AT4 receptor affinity. One ligand, with an 11-membered ring system (4), inhibited human IRAP and aminopeptidase N (AP-N) activity with similar potency as angiotensin IV but was considerably more stable than angiotensin IV toward enzymatic degradation. The compound provides a promising starting point for further optimization toward more drug-like derivatives. The cyclic constrained analogs allowed us to propose a tentative bioactive conformation of angiotensin IV and it seems that the peptide adopts an inverse gamma-turn at the C-terminal.
Collapse
Affiliation(s)
- Andreas Axén
- Department of Medicinal Chemistry, Uppsala University, Box 574, SE-75123 Uppsala, Sweden
| | | | | | | | | | | |
Collapse
|
13
|
Ito N, Nomura S, Iwase A, Ito T, Kikkawa F, Tsujimoto M, Ishiura S, Mizutani S. ADAMs, a disintegrin and metalloproteinases, mediate shedding of oxytocinase. Biochem Biophys Res Commun 2004; 314:1008-13. [PMID: 14751233 DOI: 10.1016/j.bbrc.2003.12.183] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Placental leucine aminopeptidase (P-LAP), a type-II transmembrane protease responsible for oxytocin degradation during pregnancy, is converted to a soluble form through proteolytic cleavage. The goal of this study was to determine the nature of the P-LAP secretase activity. The hydroxamic acid-based metalloprotease inhibitors GM6001 and ONO-4817 as well as the TNF-alpha protease inhibitor-2 (TAPI-2) reduced P-LAP release, while tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2, which are matrix metalloproteinase inhibitors, had no effect on P-LAP release in Chinese hamster ovary (CHO) cells stably overexpressing P-LAP, thus indicating possible involvement of ADAM (a disintegrin and metalloproteinase) members in P-LAP shedding. Furthermore, overexpression of ADAM9 and ADAM12 increased P-LAP release in P-LAP-CHO transfectants. Immunohistochemical analysis in human placenta demonstrated strong expression of ADAM12 in syncytiotrophoblasts, while little expression of ADAM9 was detected throughout the placenta. Our results suggest ADAM members, at least including ADAM12, are involved in P-LAP shedding in human placenta.
Collapse
Affiliation(s)
- Norio Ito
- Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, 466-8550, Nagoya, Japan
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Song CH, So GY, Pak SC, Jang CH, Choi BC, Flouret G, Mehendale R. Comparison of Oxytocin and Oxytocin Antagonist Metabolism in the Plasma of Pregnant Humans and Baboons. Gynecol Obstet Invest 2002; 54:21-5. [PMID: 12297713 DOI: 10.1159/000064692] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Oxytocin antagonists may be useful in inhibiting the uterine contractions of preterm labor. One such compound is TT-235 (previously referred to as Antag III). The purpose of this study was to compare the resistance of TT-235 and oxytocin to enzymatic degradation by oxytocinase in the blood of humans and baboons during their 3rd trimester of pregnancy. Blood samples from pregnant women and baboons not in labor were incubated in vitro with known amounts of oxytocin and TT-235. Samples were collected at 0, 15, 30, 45, and 60 min for oxytocin analysis and at 0, 10, 60, and 360 min for TT-235 analysis. Oxytocin was analyzed by radioimmunoassay after extraction, while TT-235 was analyzed by radioreceptor assay. In human blood, oxytocin was readily metabolized with >83% disappearance over the 60-min incubation period. In contrast, TT-235 was stable up to 360 min of incubation. In the baboon, oxytocin did not diminish over the 60-min incubation period. The level of TT-235 was similar to that in human blood without change over 360 min of incubation. This study suggests (1) that in contrast to blood from pregnant humans, blood from pregnant baboons lacks oxytocinase at least in vitro and (2) that TT-235 is resistant to enzymatic degradation by human blood, implying that this oxytocin antagonist may have a prolonged activity in vivo in humans.
Collapse
Affiliation(s)
- Chang Hun Song
- Department of Obstetrics and Gynecology, Chosun University Medical School, Gwangju, Korea
| | | | | | | | | | | | | |
Collapse
|
15
|
Abstract
Cystinyl aminopeptidase (CAP; EC 3.4.11.3) is an integral protein of the placental membrane that is also found in a soluble form in maternal serum during pregnancy. CAP was found to be shed from human placental membranes in a temperature- and time-dependent process. The released form of CAP was hydrophilic as assessed by phase separation in Triton X-114 and high-speed centrifugation. This ectodomain shedding of CAP was inhibited by the hydroxamic acid-based compounds marimastat and BB3103. The inhibition profile for the shedding of CAP was distinct to that for the release of angiotensin converting enzyme, implicating the involvement of distinct zinc metallosecretases in the shedding of these two proteins. These results have implications for our understanding of the mechanism underlying the reduction in serum levels of CAP observed in certain pregnancy-related disorders, such as pre-eclampsia.
Collapse
Affiliation(s)
- L D Ofner
- Proteolysis Research Group, School of Biochemistry and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | | |
Collapse
|
16
|
Matsumoto H, Rogi T, Yamashiro K, Kodama S, Tsuruoka N, Hattori A, Takio K, Mizutani S, Tsujimoto M. Characterization of a recombinant soluble form of human placental leucine aminopeptidase/oxytocinase expressed in Chinese hamster ovary cells. Eur J Biochem 2000; 267:46-52. [PMID: 10601849 DOI: 10.1046/j.1432-1327.2000.00949.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Serum levels of human placental leucine aminopeptidase/oxytocinase (P-LAP) increase with gestation. cDNA cloning of P-LAP revealed that the enzyme is a type II membrane-bound protein containing the consensus HEXXH(X)18E motif found in the M1 family of zinc-metallopeptidase proteins. In this study, a recombinant soluble form of P-LAP found in maternal serum was expressed in Chinese hamster ovary cells, purified to homogeneity and then characterized. Although N-terminal sequencing revealed a four-amino-acid deletion, the purified enzyme was active and was shown to be a zinc-containing homodimeric protein with molecular mass of 280 kDa in solution. Using artificial substrates, it was shown that the enzyme has broad specificity and is inhibited by several compounds known as aminopeptidase inhibitors. Subsequently, sequential N-terminal amino-acid liberation of several peptide hormones by the enzyme was monitored and structures of the products were determined. Among the hormones having a cysteine residue at their N-terminal end and intramolecular disulfide bonds, it was found that vasopressin and oxytocin, but not calcitonin and endothelins, were cleaved by the enzyme. Because the molecular properties of oxytocinase so far reported often conflict, our results provide an initial biochemical and enzymatic characterization of moleculary defined P-LAP/oxytocinase.
Collapse
Affiliation(s)
- H Matsumoto
- The Institute of Phyical and Chemical Research (RIKEN), Wako-shi, Saitama, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Mizutani S, Safwat MA, Goto K, Tsujimoto M, Nakazato H, Itakura A, Mizuno M, Kurauchi O, Kikkawa F, Tomoda Y. Initiating and responsible enzyme of arginine vasopressin degradation in human placenta and pregnancy serum. Regul Pept 1995; 59:371-8. [PMID: 8577942 DOI: 10.1016/0167-0115(95)00108-n] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The hydrolysis of arginine vasopressin (AVP) by human placental subcellular fractions and pregnancy sera was studied in the presence of selective inhibitors and the antibody against pregnancy serum oxytocinase (P-LAP) (EC 3.4.11.3) by measuring liberated amino acids by high-performance liquid chromatography (HPLC). AVP degradation by placental subcellular fractions and pregnancy sera was inhibited by bestatin. The IC50 values of bestatin on AVP degradation by placental subcellular fractions and pregnancy sera were similar to that of this inhibitor on the P-LAP measured by L-Leu-p-nitroamnilide as a substrate (LAP activity), which we reported previously. Our immunotitration study clearly showed that the initiating and responsible protease in AVP degradation in human placenta and pregnancy serum is P-LAP. Since N-benzylcarbonyl-valyl-prolinal (Z-Val-prolinal), a selective inhibitor of post-proline endopeptidase, and phosphoramidon, a putative endopeptidase-24.11 inhibitor, could not significantly influence the degradation of AVP by placental microsomal fractions. Neither enzyme seems to be actively involved in AVP degradation.
Collapse
Affiliation(s)
- S Mizutani
- Department of Obstetrics and Gynecology, Nagoya University School of medicine, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Irons DW, Davison JM, Baylis PH. Evaluation of enzyme inhibitors of cystinyl aminopeptidase and application to the measurement of immunoreactive atrial natriuretic peptide in human pregnancy. Clin Chim Acta 1994; 231:185-91. [PMID: 7889600 DOI: 10.1016/0009-8981(94)90202-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- D W Irons
- Department of Obstetrics and Gynaecology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | | | | |
Collapse
|
19
|
van der Post JA, van Heerikhuize JJ, Boer K, van Boxtel CE, Swaab DF. Radioimmunoassay of vasopressin during pregnancy. Use and removal of cystylaminopeptidase inhibitors. Clin Chim Acta 1994; 230:125-36. [PMID: 7834864 DOI: 10.1016/0009-8981(94)90265-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
This paper describes a radioimmunoassay (RIA) for arginine-vasopressin in which o-phenanthroline effectively inhibits cystyl-amino-peptidase activity in whole blood and plasma from pregnant women but in which o-phenanthroline is removed during the extraction of vasopressin from plasma to prevent disturbance of the RIA. Cystyl-amino-peptidase causes immediate degradation of vasopressin unless cystyl-amino-peptidase enzyme inhibitors such as o-phenanthroline are applied. However, o-phenanthroline interferes with RIA. We report an extraction procedure over octadecasyl silica-packed Sep-Pak C18 columns, by which cystyl-amino-peptidase as well as most of the cystyl-amino-peptidase inhibitor is removed from plasma with chloroform. The average o-phenanthroline concentration (0.25 mmol/l) found in the assay medium after extraction appeared not to interfere with the RIA. Polyacrylamide gel isoelectric focusing of extracts of platelet-rich and platelet-poor plasma from pregnant women revealed a single vasopressin immunoreactive peak in the RIA. Recovery and between-assay coefficients of variation of 3.2 ng/l vasopressin from pregnancy whole blood were comparable with non-pregnant controls (57%/8% and 59%/13%, respectively). Results with this assay compare well with those of another assay using inhibitors in pregnant subjects and with results in non-pregnant subjects.
Collapse
Affiliation(s)
- J A van der Post
- Department of Obstetrics and Gynecology, Academic Medical Center, University of Amsterdam, The Netherlands
| | | | | | | | | |
Collapse
|
20
|
Masková HP, Burbach JP, Kokotos G, Tzougraki C, Barth T. Inhibition of human serum oxytocinase (cystine aminopeptidase, E. C. 3.4.11.3) by GnRH peptides. Endocr Regul 1992; 26:53-6. [PMID: 1421209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The hydrolysis of H-Cys(Bzl)-NH-Meq by human serum oxytocinase (E.C. 3.4.11.3) was inhibited non-competitively by various pyroglutamyl peptides. The most effective were the chicken GnRH II (Ki = 6 x 10(-6) mol l-1) and salmon GnRH (Ki = 12 x 10(-6) mol l-1), while the inhibitory potency of human GnRH was substantially lower (Ki = 60.0 x 10(-6) mol l-1). Variations in inhibitory potency of individual peptides reflected mostly the differences in N-terminal and C-terminal parts of the molecules.
Collapse
Affiliation(s)
- H P Masková
- Department of Peptide Biochemistry, Czechoslovak Academy of Sciences, Praha
| | | | | | | | | |
Collapse
|
21
|
Abstract
Two isoenzymes of oxytocinase activity were fractionated from human seminal plasma by acrylamide-agarose gel chromatography and partly characterized using S-benzyl-L-cysteine-p-nitroanilide (BCN) and L-leucine-p-nitroanilide (LN) separately as substrates. These isoenzymes appeared to be metallo-aminopeptidases with different elution volumes (90 ml and 150 ml), apparent molecular weights (unknown value and 300,000) and pH optima (6.8 and 7.0 with BCN and 7.2 and 7.4 with LN), but with similar substrate affinity and thermal sensitivity, and susceptibility to EDTA, divalent metal ions, L-methionine, polypeptide hormones and prostaglandins. A comparison of the enzymic properties with pregnancy-associated oxytocinases suggests that seminal oxytocinases are related more closely to amniotic fluid isoenzymes than to pregnancy serum, placental and uterine isoenzymes.
Collapse
Affiliation(s)
- A C Roy
- Department of Obstetrics and Gynaecology, National University of Singapore, National University Hospital
| | | | | |
Collapse
|
22
|
Abstract
A technique for complete oxytocinase inhibition has been combined with a rapid serial sampling strategy to determine the plasma oxytocin concentration in eight women undergoing amniotomy for the induction of labour at term and in eight control women. Amniotomy was not associated with an increase in plasma oxytocin concentration. Furthermore, the concentrations were not increased for 20 min following the procedure. Labour was not established in any patient by the end of the 30-min study period.
Collapse
Affiliation(s)
- S Thornton
- Department of Obstetrics and Gynaecology, Princess Mary Maternity Hospital, Newcastle upon Tyne
| | | | | |
Collapse
|
23
|
Taniguchi K, Sugiyama M, Shimizu H, Azuma Y, Kanno T. [A method for the determination of cytosolic aminopeptidase in serum and its usefulness for clinical application. Selection of inhibitors for membrane-bound aminopeptidase and cystyl aminopeptidase]. Rinsho Byori 1989; 37:795-801. [PMID: 2607648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A method for the determination of cytosolic aminopeptidase (EC 3.4.11.1; C-AP) in serum was developed. At first, more specific and adequate inhibitor for other serum peptidases, such as membrane-bound aminopeptidase (EC 3.4.11.2; arylamidase, AA) and cystyl aminopeptidase (EC 3.4.11.3; CAP) was selected from 1,10-phenanthroline derivatives. The compound, 4,7-dimethyl-1,10-phenanthroline (4,7-DMP) is one of the most effective inhibitor for AA and CAP, and it inhibits completely these enzymes at the concentration of less than 0.4 mmol/l. C-AP in serum at an optimum pH of 8.0 in the assay using L-leucine amide (LA) as the substrate had no inhibitory effects at the concentration of more than 0.4 mmol/l of 4,7-DMP. The results with the proposed method correlated with those with a conventional electrophoretic method. The proposed method hence is a specific and easily available assay for C-AP in serum. The further analysis of C-AP using this method would promise the establishment of clinical assessment of the enzyme.
Collapse
|
24
|
Burd JM, Davison J, Weightman DR, Baylis PH. Evaluation of enzyme inhibitors of pregnancy associated oxytocinase: application to the measurement of plasma immunoreactive oxytocin during human labour. Acta Endocrinol (Copenh) 1987; 114:458-64. [PMID: 2436427 DOI: 10.1530/acta.0.1140458] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The presence of the human placental enzyme, oxytocinase, in blood samples taken during pregnancy causes major methological problems in the radioimmunoassay for plasma oxytocin. Inadequate inhibition of the enzyme activity may lead to spuriously high or low values of plasma oxytocin. This study systematically investigates a variety of enzyme inhibitors. The optimum inhibitory system was obtained by the addition of 10 microliters of cold 125 mmol/l 1.10 phenanthrolene and 1 mol/l EDTA per ml of whole blood into the syringe. Complete enzyme inhibition was maintained for up to 60 min, during which time the lithium heparinized plasma samples were extracted by the Florisil method. Following extraction there was no enzyme activity in the extract residue. Concentrations of phenanthrolene and EDTA necessary to eliminate enzyme activity were 50- and 10-fold greater, respectively, than in any previously reported method. Recovery of synthetic oxytocin added to pregnancy plasma with inhibitors was 80% or higher, over the concentration range 1-100 pmol/l. Extract residue could be stored at -20 degrees C for up to 7 weeks. Dilutions of pregnancy plasma extracts ran parallel to the oxytocin standard curve. Studies on plasma concentrations of oxytocin (OT) during the first stage of labour in 6 patients showed that 3 had pulsatile plasma OT, peak values ranging from 4-10 pmol/l in phase with uterine concentrations, but 2 who had regular uterine activity had no episodic changes in plasma OT. One patient with hypocontractile labour had low non-fluctuating plasma OT.
Collapse
|
25
|
Abstract
The biochemical characteristics of aminopeptidase A (EC 3.4.11.7), oxytocinase (EC 3.4.11.3) and alanyl aminopeptidase (EC 3.4.11.2) purified from serum of pregnant women were compared. Aminopeptidase A hydrolysed only acidic amino acid derivatives, whereas oxytocinase and alanyl aminopeptidase had partially overlapping broad substrate specificities. Oxytocinase showed the highest Vmax value with LeuNA but the lowest Km value with ArgNA (Km 0.059 +/- 0.08 mmol/l). Alanyl aminopeptidase hydrolysed AlaNA most rapidly, but showed the highest affinity for LysNA (Km 0.054 +/- 0.006 mmol/l). The enzymes were sensitive to EDTA. Co2+, Ni2+ and Zn2+ were able to reactivate all suppressed enzymes, but Mn2+ reactivated only aminopeptidase A after EDTA inhibition. The alkaline earth metals were activators of aminopeptidase A, while Co2+ activated only alanyl aminopeptidase. This enzyme was the most sensitive to L-amino acids. Acidic amino acids inhibited aminopeptidase A but had no effect on the two other enzymes. Oxytocinase was most sensitive to thermal treatment. Amastatin did not inhibit oxytocinase, whereas aminopeptidase A was more resistant than alanyl aminopeptidase to this effector.
Collapse
|
26
|
Sakura H, Kobayashi H, Tsuruta S, Mizutani S. Oxytocinase-like enzyme in an ovarian dysgerminoma: a placenta-specific protein. Biochem Med 1985; 34:195-202. [PMID: 4084242 DOI: 10.1016/0006-2944(85)90111-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Aminopeptidase from dysgerminoma was purified and characterized using L-leucine-beta-naphthylamide as substrate. The enzyme was resistant to puromycin, methionine, amastatin, bastatin, and EDTA, and it was heat labile at 60 degrees C. The enzyme showed the same electrophoretic mobility as pregnant-patient serum oxytocinase CAP1 on polyacrylamide gel electrophoresis. Km value against S-benzylcysteine-p-nitroanilide was 4.2 X 10(-4) M. Oxytocin and vasopressin competitively inhibited the enzyme activity. Molecular weight of the enzyme was estimated to be 80,000 by Sephadex G-200 column chromatography. These results suggest that aminopeptidase from dysgerminoma is an oxytocinase-like enzyme, a placenta-specific protein.
Collapse
|
27
|
Roy AC, Yeang M, Tan SM, Kottegoda SR, Ratnam SS. Prostaglandins, not cyclic GMP, inhibit oxytocinase isoenzymes from human amniotic fluid in vitro. Prostaglandins 1985; 30:255-61. [PMID: 2996058 DOI: 10.1016/0090-6980(85)90189-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Two isoenzymes of oxytocinase (EC 3.4.11.3) activity were fractionated from human amniotic fluid samples between the 14th and 22nd weeks of gestation by Ultrogel acrylamide-agarose gel filtration and partially characterized. The isoenzymes were competitively inhibited by PGE1, PGE2 and PGF2 alpha more at pH 6.2 than at pH 6.8, whereas cyclic GMP (cGMP) and its 8-bromo derivative had no effect at either pH. The implications of these findings are discussed and it is suggested that since the activity of amniotic fluid oxytocinases is very low or minimal at or near term, inhibition of these by prostaglandins may not have physiological significance in the initiation of human parturition.
Collapse
|
28
|
Roy AC, Yeang M, Kottegoda SR, Ratnam SS. Selective inhibition of multimolecular forms of human serum and placental oxytocinase activity by prostaglandins and cyclic GMP. Prostaglandins Leukot Med 1984; 14:105-11. [PMID: 6328538 DOI: 10.1016/0262-1746(84)90028-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Ultrogel acrylamide-agarose chromatography was employed for fractionation of oxytocinase isoenzymes from serum of pregnant women and from human placenta. Using S-benzyl-L-cysteine-p-nitroanilide ( BCN ) and L-leucine-p-nitroanilide (LN) as substrates, three activity peaks (PI, PII, PIII) from placenta, and one peak (SI) from serum were identified. SI coincided with PII, and with all isoenzymes the hydrolysis of LN was greater than that of BCN . Prostaglandins E1, E2 and F2 alpha inhibited all oxytocinases , more potently the hydrolysis of LN than BCN and at pH 6.2 than at pH 6.8. Although cyclic GMP and its 8-bromo derivative similarly inhibited these isoenzymes except PIII, they were considerably more effective against the hydrolysis of BCN than LN.
Collapse
|
29
|
Roy AC, Karim SM. Review: significance of the inhibition by prostaglandins and cyclic GMP of oxytocinase activity in human pregnancy and labour. Prostaglandins 1983; 25:55-70. [PMID: 6302740 DOI: 10.1016/0090-6980(83)90135-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The uterotonic action of oxytocin has been known for many decades. This neurohypophysial hormone is thought to play a functional role in human parturition. Since 1968, prostaglandins have also been implicated in parturition. These two groups of uterotonic agents have now a recognized therapeutic role, and are widely used in the induction of labour and in fertility control. However, the mechanism of action and the interrelationship between these endogenous compounds in pregnancy are poorly understood. In this article, the role and interaction of oxytocin, oxytocinase and prostaglandins in human pregnancy and labour have been reviewed. Inhibition of oxytocinase activity by prostaglandins has been suggested as a mechanism in parturition. Possible involvement of cyclic GMP in the initiation of labour has also been discussed.
Collapse
|
30
|
Abstract
The effect of prostaglandins (PGs) and other compounds on human serum oxytocinase (EC 3.4.11.3) activity in vitro was studied by a sensitive assay using S-benzyl-L-cysteine-p-nitroanilide as substrate. PGE1, PGE2 and PGF2 alpha significantly inhibited serum oxytocinase activity in a dose-related manner and in decreasing order of potency. cGMP, 8-bromo-cGMP, indomethacin, polyphloretin phosphate, hypertonic saline and urea were also active. cAMP, db-cAMP, 8-bromo-cAMP, db-cGMP, 5'-AMP, 5'-ADP, 5'-ATP, 5'-GDP, 5'-GTP, aspirin, sodium salicylate, paracetamol, theophylline and IBMX did not inhibit the enzyme activity. The results suggest that the oxytocic action of prostaglandins may be due, at least in part, to an inhibition of oxytocinase activity.
Collapse
|
31
|
Lampelo S, Vanha-Perttula T. Fractionation and characterization of cystine aminopeptidase (oxytocinase) and arylamidase of human serum during pregnancy. J Reprod Fertil 1980; 58:225-35. [PMID: 6767028 DOI: 10.1530/jrf.0.0580225] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Cystine aminopeptidase and arylamidase activities in human serum were determined by enzymic hydrolysis of L-cystine-di-beta-naphthylamide (CysNA) and L-leucine-beta-naphthylamide (LeuNA), respectively. The activities of both enzymes increased during pregnancy, cystine aminopeptidase 12.5-fold and arylamidase 8.3-fold. Serum CysNA and LeuNA hydrolysing aminopeptidases were separated by gel filtration on Sepharose 6B. Serum from non-pregnant women (control) contained arylamidase (Ic), which hydrolysed LeuNA and (weakly) CysNA, and cystine aminopeptidase II, hydrolysing only CysNA. During pregnancy a new enzyme appeared in maternal serum and showed cystine aminopeptidase and arylamidase activity (Im). Maternal serum Enzyme(s) I had higher pH optima (6.5 with CysNA; 7.5 with LeuNA) and higher molecular weights (309,000) than arylamidase Ic (pH optima at 5.52-5.5 with CysNA and 7.0 with LeuN; mol.wt approximately 130,000). Arylamidase Ic was more sensitive to L-methionine, but more resistant to heat than maternal serum Enzyme(s) I. Both control and maternal serum Enzyme(s) I were inhibited by EDTA, but were re-activated by Zn2+ and Co2+ with LeuNA and CysNA as substrates and by Ni2+ with CysNA. Cystine aminopeptidase Im and arylamidase Im may be a single enzyme although differences were obtained in pH optima and reactivation by Ni2+ after EDTA treatment. Since maternal serum Enzyme(s) I had biochemical characteristics similar to those of placental aminopeptidase(s) I, it is suggested that the activities are of placental origin. Cystine aminopeptidase II appeared in all sera. It differed clearly from both maternal and control serum enzyme(s) I: it had the lowest molecular weight (76,000), a different pH optimum (6.0) and was resistant to EDTA and L-methionine. It was not as effectively inhibited by Ni2+ as was Enzyme(s) I.
Collapse
|
32
|
|
33
|
Himaya A, Pathak SM, Nuyens AJ, Krzaniak S, Taylor GO. The effect of various drugs on maternal serum cystine aminopeptidase. Eur J Obstet Gynecol Reprod Biol 1977; 7:377-82. [PMID: 264065 DOI: 10.1016/0028-2243(77)90067-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Serial estimations (87) of serum cystine aminopeptidase (CAP) in pregnant women (18) using diphenyl hydantoin, phenobarbital or diazepam revealed that the enzyme levels were below the average for normals in 89% of patients. The initially low CAP levels in women on diazepam were improved within 24 h after betamethasone administration. Subsequent studies in vitro confirmed that diphenyl hydantoin, phenobarbital, diazepam and acetyl salicylate markedly inhibited CAP levels in sera of women (72) with clinically uncomplicated pregnancy. No inhibition of CAP by any of the drugs tested was observed in sera from nonpregnant women (8). However, nonpregnant women receiving medroxyprogesterone acetate injections showed CAP inhibition by various drugs, suggesting some changes in the enzyme moiety under the influence of the hormone.
Collapse
|
34
|
Kleiner H, Brouet-Yager M. [Study of pregnancy serum L-cystine-di-beta-naphthylamide hydrolase ("oxytocinase") by a 2-hour assay (author's transl)]. Clin Chim Acta 1973; 48:299-309. [PMID: 4765710 DOI: 10.1016/0009-8981(73)90200-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
|