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Wang Y, Li S, Yan Z, Guo Y, Zhang L. Computational insights into novel inhibitor indole-heterocycle specific against glycogen phosphorylase isoenzymes interaction mechanism. Future Med Chem 2023; 15:913-922. [PMID: 37395076 DOI: 10.4155/fmc-2023-0084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023] Open
Abstract
Background: Glycogen phosphorylase (GP) is a potential drug target. As the three subtypes of GP are highly conserved, it is difficult to research their specificity. However, compound 1 inhibits the GP subtypes differently and was studied to aid in designing specific inhibitors. Results: Molecular docking showed that the ligands in GP subtype complexes had some differences in spatial conformation and binding modes, stabilized by polar and nonpolar interactions. The results were confirmed through kinetic experiments, with affinities of -85.230 (brain GP), -73.809 (liver GP) and -66.061 kJ/mol (muscle GP). Conclusion: The study provides insight into the possible reasons for differences in compound 1's inhibitory activity against the GP subtypes and offers guidance in designing target molecules for regulating selectivity among the subtypes.
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Affiliation(s)
- Youde Wang
- Key Laboratory of Traditional Chinese Medicine Research & Development of Hebei Province, Institute of Traditional Chinese Medicine, Chengde Medical University, Chengde, 067000, China
| | - Shuai Li
- Key Laboratory of Traditional Chinese Medicine Research & Development of Hebei Province, Institute of Traditional Chinese Medicine, Chengde Medical University, Chengde, 067000, China
| | - Zhiwei Yan
- Key Laboratory of Traditional Chinese Medicine Research & Development of Hebei Province, Institute of Traditional Chinese Medicine, Chengde Medical University, Chengde, 067000, China
| | - Yachun Guo
- Department of Pathogen Biology, Chengde Medical University, Chengde, Hebei, 067000, China
| | - Liying Zhang
- Key Laboratory of Traditional Chinese Medicine Research & Development of Hebei Province, Institute of Traditional Chinese Medicine, Chengde Medical University, Chengde, 067000, China
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2
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Drakou CE, Gardeli C, Tsialtas I, Alexopoulos S, Mallouchos A, Koulas SM, Tsagkarakou AS, Asimakopoulos D, Leonidas DD, Psarra AMG, Skamnaki VT. Affinity Crystallography Reveals Binding of Pomegranate Juice Anthocyanins at the Inhibitor Site of Glycogen Phosphorylase: The Contribution of a Sugar Moiety to Potency and Its Implications to the Binding Mode. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:10191-10199. [PMID: 32840370 DOI: 10.1021/acs.jafc.0c04205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Anthocyanins (ACNs) are dietary phytochemicals with an acknowledged therapeutic significance. Pomegranate juice (PJ) is a rich source of ACNs with potential applications in nutraceutical development. Glycogen phosphorylase (GP) catalyzes the first step of glycogenolysis and is a molecular target for the development of antihyperglycemics. The inhibitory potential of the ACN fraction of PJ is assessed through a combination of in vitro assays, ex vivo investigation in hepatic cells, and X-ray crystallography studies. The ACN extract potently inhibits muscle and liver isoforms of GP. Affinity crystallography reveals the structural basis of inhibition through the binding of pelargonidin-3-O-glucoside at the GP inhibitor site. The glucopyranose moiety is revealed as a major determinant of potency as it promotes a structural binding mode different from that observed for other flavonoids. This inhibitory effect of the ACN scaffold and its binding mode at the GP inhibitor binding site may have significant implications for future structure-based drug design endeavors.
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Affiliation(s)
- Christina E Drakou
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis 41500, Larisa, Greece
| | - Chrysavgi Gardeli
- Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens 118 55, Greece
| | - Ioannis Tsialtas
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis 41500, Larisa, Greece
| | - Serafeim Alexopoulos
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis 41500, Larisa, Greece
| | - Athanasios Mallouchos
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis 41500, Larisa, Greece
| | - Symeon M Koulas
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis 41500, Larisa, Greece
| | - Anastasia S Tsagkarakou
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis 41500, Larisa, Greece
| | - Demetres Asimakopoulos
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis 41500, Larisa, Greece
| | - Demetres D Leonidas
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis 41500, Larisa, Greece
| | - Anna-Maria G Psarra
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis 41500, Larisa, Greece
| | - Vasiliki T Skamnaki
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis 41500, Larisa, Greece
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3
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Balliu A, Baltzer L. Exploring Non-obvious Hydrophobic Binding Pockets on Protein Surfaces: Increasing Affinities in Peptide-Protein Interactions. Chembiochem 2017; 18:1396-1407. [PMID: 28432776 DOI: 10.1002/cbic.201700048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Indexed: 11/06/2022]
Abstract
A 42-residue polypeptide conjugated to a small-molecule organic ligand capable of targeting the phosphorylated side chain of Ser15 was shown to bind glycogen phosphorylase a (GPa) with a KD value of 280 nm. The replacement of hydrophobic amino acids by Ala reduced affinities, whereas the incorporation of l-2-aminooctanoic acid (Aoc) increased them. Replacing Nle5, Ile9 and Leu12 by Aoc reduced the KD value from 280 to 27 nm. "Downsizing" the 42-mer to an undecamer gave rise to an affinity for GPa an order of magnitude lower, but the undecamer in which Nle5, Ile9 and Leu12 were replaced by Aoc showed a KD value of 550 nm, comparable with that of the parent 42-mer. The use of Aoc residues offers a convenient route to increased affinity in protein recognition as well as a strategy for the "downsizing" of peptides essentially without loss of affinity. The results show that hydrophobic binding sites can be found on protein surfaces by comparing the affinities of polypeptide conjugates in which Aoc residues replace Nle, Ile, Leu or Phe with those of their unmodified counterparts. Polypeptide conjugates thus provide valuable opportunities for the optimization of peptides and small organic compounds in biotechnology and biomedicine.
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Affiliation(s)
- Aleksandra Balliu
- Department of Chemistry, BMC, Uppsala University, P. O. Box 576, 751 23, Uppsala, Sweden
| | - Lars Baltzer
- Department of Chemistry, BMC, Uppsala University, P. O. Box 576, 751 23, Uppsala, Sweden
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4
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Nakamura M, Makino Y, Takagi C, Yamagaki T, Sato M. Probing the catalytic site of rabbit muscle glycogen phosphorylase using a series of specifically modified maltohexaose derivatives. Glycoconj J 2017; 34:563-574. [PMID: 28597243 DOI: 10.1007/s10719-017-9776-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/12/2017] [Accepted: 05/15/2017] [Indexed: 02/05/2023]
Abstract
Glycogen phosphorylase (GP) is an allosteric enzyme whose catalytic site comprises six subsites (SG1, SG-1, SG-2, SG-3, SG-4, and SP) that are complementary to tandem five glucose residues and one inorganic phosphate molecule, respectively. In the catalysis of GP, the nonreducing-end glucose (Glc) of the maltooligosaccharide substrate binds to SG1 and is then phosphorolyzed to yield glucose 1-phosphate. In this study, we probed the catalytic site of rabbit muscle GP using pyridylaminated-maltohexaose (Glcα1-4Glcα1-4Glcα1-4Glcα1-4Glcα1-4GlcPA, where GlcPA = 1-deoxy-1-[(2-pyridyl)amino]-D-glucitol]; abbreviated as PA-0) and a series of specifically modified PA-0 derivatives (Glc m -AltNAc-Glc n -GlcPA, where m + n = 4 and AltNAc is 3-acetoamido-3-deoxy-D-altrose). PA-0 served as an efficient substrate for GP, whereas the other PA-0 derivatives were not as good as the PA-0, indicating that substrate recognition by all the SG1 -SG-4 subsites was important for the catalysis of GP. By comparing the initial reaction rate toward the PA-0 derivatives (V derivative) with that toward PA-0 (V PA-0), we found that the value of V derivative/V PA-0 decreased significantly as the level of allosteric activation of GP increased. These results suggest that some conformational changes have taken place in the maltooligosaccharide-binding region of the GP catalytic site during allosteric regulation.
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Affiliation(s)
- Makoto Nakamura
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka, 599-8531, Japan
| | - Yasushi Makino
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka, 599-8531, Japan.
| | - Chika Takagi
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka, 599-8531, Japan
| | - Tohru Yamagaki
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan
| | - Masaaki Sato
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka, 599-8531, Japan
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5
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Murugavel S, Jacob Prasanna Stephen CS, Subashini R, AnanthaKrishnan D. Synthesis, structural elucidation, antioxidant, CT-DNA binding and molecular docking studies of novel chloroquinoline derivatives: Promising antioxidant and anti-diabetic agents. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2017; 173:216-230. [PMID: 28599239 DOI: 10.1016/j.jphotobiol.2017.05.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/29/2017] [Accepted: 05/30/2017] [Indexed: 12/15/2022]
Abstract
The synthesized novel chloroquinoline derivatives 1-(2-chloro-4-phenylquinolin-3-yl)ethanone (CPQE), 1-(2,6-dichloro-4-phenylquinolin-3-yl)ethanone (DCPQE), methyl 2,6-dichloro-4-phenylquinoline-3-carboxylate (MDCPQC),methyl 2-chloro-4-methylquinoline-3-carboxylate (MCMQC) were subjected to the elementary analysis like FT-IR, NMR and Mass spectra using GCMS. Also, single crystal X-ray diffraction study was executed for the compound MDCPQC. The crystal packing is stabilized by C-H…π and π-π interactions and also Chlorine-Chlorine short intermolecular contacts generating a three-dimensional supramolecular network. The antioxidant activity reduces high glucose level in the human body and hence the synthesized compounds were subjected for the estimation of antioxidant activity using DPPH method which exhibited good percentage of inhibition in comparison with ascorbic acid, a well-known anti-oxidant. The binding interaction of the chloroquinoline derivatives with calf thymus DNA (CT-DNA) has been explored by fluorescence quenching studies and molecular docking analysis has been employed to confirm the nature of binding. The prediction of pharmacological properties such as drug-likeness, molecular properties like absorption, distribution, metabolism, excretion and toxicity (ADMET) was carried out by computational studies to compare chloroquinoline derivatives with standard drug. Owing to the various potential biological activities of the quinoline compounds, molecular docking studies were also further carried out for the chloroquinoline derivatives, showing that they may act as effective anti-diabetic agents by inhibiting Glycogen Phosphorylase a protein.
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Affiliation(s)
- S Murugavel
- Department of Physics, Thanthai Periyar Government Institute of Technology, Vellore 632 002, Tamilnadu, India.
| | - C S Jacob Prasanna Stephen
- Department of Physics, Global Institute of Engineering and Technology, Melvisharam, Vellore 632 509, Tamilnadu, India
| | - R Subashini
- Department of Chemistry, Arignar Anna Government Arts College for Women, Walajapet, Vellore, Tamilnadu, India
| | - Dhanabalan AnanthaKrishnan
- Bioinformatics infrastructure facility, University of Madras, Guindy Campus, Chennai 600 025, Tamilnadu, India
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6
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Galal SA, Khattab M, Andreadaki F, Chrysina ED, Praly JP, Ragab FA, El Diwani HI. Synthesis of (benzimidazol-2-yl)aniline derivatives as glycogen phosphorylase inhibitors. Bioorg Med Chem 2016; 24:5423-5430. [DOI: 10.1016/j.bmc.2016.08.069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 08/28/2016] [Accepted: 08/31/2016] [Indexed: 11/30/2022]
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7
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Role of glycogen phosphorylase in liver glycogen metabolism. Mol Aspects Med 2015; 46:34-45. [PMID: 26519772 DOI: 10.1016/j.mam.2015.09.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 02/05/2023]
Abstract
Liver glycogen is synthesized after a meal in response to an increase in blood glucose concentration in the portal vein and endocrine and neuroendocrine signals, and is degraded to glucose between meals to maintain blood glucose homeostasis. Glycogen degradation and synthesis during the diurnal cycle are mediated by changes in the activities of phosphorylase and glycogen synthase. Phosphorylase is regulated by phosphorylation of serine-14. Only the phosphorylated form of liver phosphorylase (GPa) is catalytically active. Interconversion between GPa and GPb (unphosphorylated) is dependent on the activities of phosphorylase kinase and of phosphorylase phosphatase. The latter comprises protein phosphatase-1 in conjunction with a glycogen-targeting protein (G-subunit) of the PPP1R3 family. At least two of six G-subunits (GL and PTG) expressed in liver are involved in GPa dephosphorylation. GPa to GPb interconversion is dependent on the conformational state of phosphorylase which can be relaxed (R) or tense (T) depending on the concentrations of allosteric effectors such as glucose, glucose 6-phosphate and adenine nucleotides and on the acetylation state of lysine residues. The G-subunit, GL, encoded by PPP1R3B gene is expressed at high levels in liver and can function as a phosphorylase phosphatase and a synthase phosphatase and has an allosteric binding site for GPa at the C-terminus which inhibits synthase phosphatase activity. GPa to GPb conversion is a major upstream event in the regulation of glycogen synthesis by glucose, its downstream metabolites and extracellular signals such as insulin and neurotransmitters.
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8
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Fazal E, Panicker CY, Varghese HT, Nagarajan S, Sudha BS, War JA, Srivastava SK, Harikumar B, Anto PL. Spectroscopic investigation (FT-IR, FT-Raman), HOMO-LUMO, NBO analysis and molecular docking study of 4-chlorophenyl quinoline-2-carboxylate. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 145:260-269. [PMID: 25791883 DOI: 10.1016/j.saa.2015.01.089] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 01/11/2015] [Accepted: 01/29/2015] [Indexed: 06/04/2023]
Abstract
FT-IR and FT-Raman spectra of 4-chlorophenyl quinoline-2-carboxylate were recorded and analyzed. The vibrational wavenumbers were computed using DFT quantum chemical calculations. The data obtained from wavenumber calculations are used to assign vibrational bands obtained experimentally. Potential energy distribution was done using GAR2PED program. The geometrical parameters obtained theoretically are in agreement with the XRD data. NBO analysis, HOMO-LUMO, first hyperpolarizability and molecular electrostatic potential results are also reported. The calculated hyperpolarizability of the title compound is 77.53 times that of the standard NLO material urea and the title compound and its derivatives are attractive object for future studies of nonlinear optical properties. Molecular docking results suggest that the compound might exhibit inhibitory activity against GPb.
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Affiliation(s)
- E Fazal
- Department of Chemistry, Yuvaraja's College, Mysore, India
| | - C Yohannan Panicker
- Department of Physics, TKM College of Arts and Science, Kollam, Kerala, India.
| | | | - S Nagarajan
- Department of Spice and Flavour Science, CSIR Central Food Technology Research Institute, Mysore, India
| | - B S Sudha
- Department of Chemistry, Yuvaraja's College, Mysore, India
| | - Javeed Ahamad War
- Department of Chemistry, Dr. H.S. Gour Central University, Sagar, M.P. 470003, India
| | - S K Srivastava
- Department of Chemistry, Dr. H.S. Gour Central University, Sagar, M.P. 470003, India
| | - B Harikumar
- Department of Chemistry, TKM College of Arts and Science, Kollam, Kerala, India
| | - P L Anto
- Department of Physics, Christ College, Iringalakkuda, Thrissur, Kerala, India
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9
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Fazal E, Panicker CY, Varghese HT, Nagarajan S, Sudha BS, War JA, Srivastava SK, Harikumar B, Anto PL. Vibrational spectroscopic and molecular docking study of 4-Methylphenylquinoline-2-carboxylate. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 143:213-222. [PMID: 25733248 DOI: 10.1016/j.saa.2015.01.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 01/11/2015] [Accepted: 01/15/2015] [Indexed: 06/04/2023]
Abstract
FT-IR and FT-Raman spectra of 4-Methylphenylquinoline-2-carboxylate were recorded and analyzed. The structure of the molecule has been optimized and structural characteristics have been determined by density functional theory. The geometrical parameters (DFT) are in agreement with the XRD results. HOMO and LUMO and other chemical properties are reported. Nonlinear optical properties are also reported. A detailed molecular picture of the title compound and its interactions were obtained from NBO analysis. The negative (red and yellow) regions of the MEP are related to electrophilic reactivity and the positive (blue) regions to nucleophilic reactivity, as shown in the MEP plot and the carbonyl group and the phenyl rings are observed as electrophilic. PASS analysis predicts that the 4-Methylphenylquinoline-2-carboxylate might exhibit anti-diabetic activity. Molecular docking results suggest that the compound might exhibit inhibitory activity against GPb.
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Affiliation(s)
- E Fazal
- Department of Chemistry, Yuvaraja's College, Mysore, India
| | - C Yohannan Panicker
- Department of Physics, TKM College of Arts and Science, Kollam, Kerala, India.
| | | | - S Nagarajan
- Department of Spice and Flavour Science, CSIR-Central Food Technology Research Institute, Mysore, India
| | - B S Sudha
- Department of Chemistry, Yuvaraja's College, Mysore, India
| | - Javeed Ahamad War
- Department of Chemistry, Dr. H.S. Gour Central University, Sagar, M.P. 470003, India
| | - S K Srivastava
- Department of Chemistry, Dr. H.S. Gour Central University, Sagar, M.P. 470003, India
| | - B Harikumar
- Department of Chemistry, TKM College of Arts and Science, Kollam, Kerala, India
| | - P L Anto
- Department of Physics, Christ College, Iringalakkuda, Thrissur, Kerala, India
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Herowati R, Widodo GP. Molecular Docking Studies of Chemical Constituents of Tinospora cordifolia on Glycogen Phosphorylase. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.proche.2014.12.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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11
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Sharov VS, Galeva NA, Dremina ES, Williams TD, Schöneich C. Inactivation of rabbit muscle glycogen phosphorylase b by peroxynitrite revisited: does the nitration of Tyr613 in the allosteric inhibition site control enzymatic function? Arch Biochem Biophys 2008; 484:155-66. [PMID: 19146822 DOI: 10.1016/j.abb.2008.12.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 12/22/2008] [Accepted: 12/22/2008] [Indexed: 11/28/2022]
Abstract
There is increasing evidence that sequence-specific formation of 3-nitrotyrosine (3-NT) may cause functional changes in target proteins. Recently, the nitration of Tyr residues in glycogen phosphorylase b (Ph-b) was implicated in the age-associated decline of protein function [Sharov et al., Exp. Gerontol. 41 (2006) 407-416]; in another report, the nitration of one specific residue, Tyr613, located in the allosteric inhibition site was hypothesized as a rationale for peroxynitrite inactivation [Dairou et al., J. Mol. Biol. 372 (2007) 1009-1021]. In this study, we have optimized the analysis of in-gel Ph-b digests by high performance liquid chromatography-electro spray ionization-tandem mass spectrometry, in order to achieve a quantitative analysis of nitration of individual Tyr residues at a high coverage of Tyr-containing sequences (92%). Our data do not confirm the role of Tyr613 nitration in the control of enzymatic function. Furthermore, we show here that the enzymatic activity of Ph-b does not directly correlate with the protein nitration levels, and that the modification of Cys and, potentially, other amino acid residues can better rationalize Ph-b inactivation by peroxynitrite.
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Affiliation(s)
- Victor S Sharov
- Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, USA
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12
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Kelsall IR, Munro S, Hallyburton I, Treadway JL, Cohen PTW. The hepatic PP1 glycogen-targeting subunit interaction with phosphorylaseacan be blocked by C-terminal tyrosine deletion or an indole drug. FEBS Lett 2007; 581:4749-53. [PMID: 17870073 DOI: 10.1016/j.febslet.2007.08.073] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2007] [Revised: 08/28/2007] [Accepted: 08/29/2007] [Indexed: 11/16/2022]
Abstract
The inhibition of hepatic glycogen-associated protein phosphatase-1 (PP1-G(L)) by glycogen phosphorylase a prevents the dephosphorylation and activation of glycogen synthase, suppressing glycogen synthesis when glycogenolysis is activated. Here, we show that a peptide ((280)LGPYY(284)) comprising the last five amino acids of G(L) retains high-affinity interaction with phosphorylase a and that the two tyrosines play crucial roles. Tyr284 deletion abolishes binding of phosphorylase a to G(L) and replacement by phenylalanine is insufficient to restore high-affinity binding. We show that a phosphorylase inhibitor blocks the interaction of phosphorylase a with the G(L) C-terminus, suggesting that the latter interaction could be targeted to develop an anti-diabetic drug.
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Affiliation(s)
- Ian R Kelsall
- Medical Research Council, Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
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13
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Freeman S, Bartlett JB, Convey G, Hardern I, Teague JL, Loxham SJG, Allen JM, Poucher SM, Charles AD. Sensitivity of glycogen phosphorylase isoforms to indole site inhibitors is markedly dependent on the activation state of the enzyme. Br J Pharmacol 2006; 149:775-85. [PMID: 17016495 PMCID: PMC2014651 DOI: 10.1038/sj.bjp.0706925] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Inhibition of hepatic glycogen phosphorylase is a potential treatment for glycaemic control in type 2 diabetes. Selective inhibition of the liver phosphorylase isoform could minimize adverse effects in other tissues. We investigated the potential selectivity of two indole site phosphorylase inhibitors, GPi688 and GPi819. EXPERIMENTAL APPROACH The activity of glycogen phosphorylase was modulated using the allosteric effectors glucose or caffeine to promote the less active T state, and AMP to promote the more active R state. In vitro potency of indole site inhibitors against liver and muscle glycogen phosphorylase a was examined at different effector concentrations using purified recombinant enzymes. The potency of GPi819 was compared with its in vivo efficacy at raising glycogen concentrations in liver and muscle of Zucker (fa/fa) rats. KEY RESULTS In vitro potency of indole site inhibitors depended upon the activity state of phosphorylase a. Both inhibitors showed selectivity for liver phosphorylase a when the isoform specific activities were equal. After 5 days dosing of GPi819 (37.5 micromol kg(-1)), where free compound levels in plasma and tissue were at steady state, glycogen elevation was 1.5-fold greater in soleus muscle than in liver (P < 0.05). CONCLUSIONS AND IMPLICATIONS The in vivo selectivity of GPi819 did not match that seen in vitro when the specific activities of phosphorylase a isoforms are equal. This suggests T state promoters may be important physiological regulators in skeletal muscle. The greater efficacy of indole site inhibitors in skeletal muscle has implications for the overall safety profile of such drugs.
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Affiliation(s)
- S Freeman
- Cardiovascular and Gastrointestinal Discovery Department, AstraZeneca, Macclesfield, Cheshire, UK.
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14
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Yanase M, Takata H, Fujii K, Takaha T, Kuriki T. Cumulative effect of amino acid replacements results in enhanced thermostability of potato type L alpha-glucan phosphorylase. Appl Environ Microbiol 2005; 71:5433-9. [PMID: 16151135 PMCID: PMC1214682 DOI: 10.1128/aem.71.9.5433-5439.2005] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The thermostability of potato type L alpha-glucan phosphorylase (EC 2.4.1.1) was enhanced by random and site-directed mutagenesis. We obtained three single-residue mutations-Phe39-->Leu (F39L), Asn135-->Ser (N135S), and Thr706-->Ile (T706I)-by random mutagenesis. Although the wild-type enzyme was completely inactivated, these mutant enzymes retained their activity even after heat treatment at 60 degrees C for 2 h. Combinations of these mutations were introduced by site-directed mutagenesis. The simultaneous mutation of two (F39L/N135S, F39L/T706I, and N135S/T706I) or three (F39L/N135S/T706I) residues further increased the thermostability of the enzyme, indicating that the effect of the replacement of the residues was cumulative. The triple-mutant enzyme, F39L/N135S/T706I, retained 50% of its original activity after heat treatment at 65 degrees C for 20 min. Further analysis indicated that enzymes with a F39L or T706I mutation were resistant to possible proteolytic degradation.
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Affiliation(s)
- Michiyo Yanase
- Biochemical Research Laboratory, Ezaki Glico Co. Ltd., 4-6-5 Utajima, Nishiyodogawa-ku, Osaka 555-8502, Japan.
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