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Calcagno D, Perina ML, Zingale GA, Pandino I, Tuccitto N, Oliveri V, Parravano MC, Grasso G. Detection of insulin oligomeric forms by a novel surface plasmon resonance-diffusion coefficient based approach. Protein Sci 2024; 33:e4962. [PMID: 38501507 PMCID: PMC10949399 DOI: 10.1002/pro.4962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 02/22/2024] [Accepted: 02/25/2024] [Indexed: 03/20/2024]
Abstract
Insulin is commonly used to treat diabetes and undergoes aggregation at the site of repeated injections in diabetic patients. Moreover, aggregation is also observed during its industrial production and transport and should be avoided to preserve its bioavailability to correctly adjust glucose levels in diabetic patients. However, monitoring the effect of various parameters (pH, protein concentration, metal ions, etc.) on the insulin aggregation and oligomerization state is very challenging. In this work, we have applied a novel Surface Plasmon Resonance (SPR)-based experimental approach to insulin solutions at various experimental conditions, monitoring how its diffusion coefficient is affected by pH and the presence of metal ions (copper and zinc) with unprecedented sensitivity, precision, and reproducibility. The reported SPR method, hereby applied to a protein for the first time, besides giving insight into the insulin oligomerization and aggregation phenomena, proved to be very robust for determining the diffusion coefficient of any biomolecule. A theoretical background is given together with the software description, specially designed to fit the experimental data. This new way of applying SPR represents an innovation in the bio-sensing field and expanding the potentiality of commonly used SPR instruments well over the canonical investigation of biomolecular interactions.
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Affiliation(s)
| | | | | | | | - Nunzio Tuccitto
- Dipartimento di Scienze ChimicheUniversity of CataniaCataniaItaly
| | | | | | - Giuseppe Grasso
- Dipartimento di Scienze ChimicheUniversity of CataniaCataniaItaly
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2
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Roy D, Maity NC, Kumar S, Maity A, Ratha BN, Biswas R, Maiti NC, Mandal AK, Bhunia A. Modulatory role of copper on hIAPP aggregation and toxicity in presence of insulin. Int J Biol Macromol 2023; 241:124470. [PMID: 37088193 DOI: 10.1016/j.ijbiomac.2023.124470] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/24/2023] [Accepted: 04/12/2023] [Indexed: 04/25/2023]
Abstract
Aggregation of the human islets amyloid polypeptide, or hIAPP, is linked to β-cell death in type II diabetes mellitus (T2DM). Different pancreatic β-cell environmental variables such as pH, insulin and metal ions play a key role in controlling the hIAPP aggregation. Since insulin and hIAPP are co-secreted, it is known from numerous studies that insulin suppresses hIAPP fibrillation by preventing the initial dimerization process. On the other hand, zinc and copper each have an inhibitory impact on hIAPP fibrillation, but copper promotes the production of toxic oligomers. Interestingly, the insulin oligomeric equilibrium is controlled by the concentration of zinc ions when the effect of insulin and zinc has been tested together. Lower zinc concentrations cause the equilibrium to shift towards the monomer and dimer states of insulin, which bind to monomeric hIAPP and stop it from developing into a fibril. On the other hand, the combined effects of copper and insulin have not yet been done. In this study, we have demonstrated how the presence of copper affects hIAPP aggregation and the toxicity of the resultant conformers with or without insulin. For this purpose, we have used a set of biophysical techniques, including NMR, fluorescence, CD etc., in combination with AFM and cell cytotoxicity assay. In the presence and/or absence of insulin, copper induces hIAPP to form structurally distinct stable toxic oligomers, deterring the fibrillation process. More specifically, the oligomers generated in the presence of insulin have slightly higher toxicity than those formed in the absence of insulin. This research will increase our understanding of the combined modulatory effect of two β-cell environmental factors on hIAPP aggregation.
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Affiliation(s)
- Dipanwita Roy
- Department of Biophysics, Bose Institute, Unified Academic Campus, Salt Lake, Sctor V, Kolkata 700091, India
| | - Narayan Chandra Maity
- Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Sector-III, Salt Lake, Kolkata 700106, India
| | - Sourav Kumar
- Department of Biophysics, Bose Institute, Unified Academic Campus, Salt Lake, Sctor V, Kolkata 700091, India
| | - Anupam Maity
- Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Bhisma N Ratha
- Department of Biophysics, Bose Institute, Unified Academic Campus, Salt Lake, Sctor V, Kolkata 700091, India
| | - Ranjit Biswas
- Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Sector-III, Salt Lake, Kolkata 700106, India
| | - Nakul Chandra Maiti
- Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Atin Kumar Mandal
- Division of Molecular Medicine, Bose Institute, Unified Academic Campus, Salt Lake, Sctor V, Kolkata, 700091, India
| | - Anirban Bhunia
- Department of Biophysics, Bose Institute, Unified Academic Campus, Salt Lake, Sctor V, Kolkata 700091, India.
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Pal I, Dey SG. The Role of Heme and Copper in Alzheimer's Disease and Type 2 Diabetes Mellitus. JACS AU 2023; 3:657-681. [PMID: 37006768 PMCID: PMC10052274 DOI: 10.1021/jacsau.2c00572] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 12/23/2022] [Accepted: 12/23/2022] [Indexed: 06/19/2023]
Abstract
Beyond the well-explored proposition of protein aggregation or amyloidosis as the central event in amyloidogenic diseases like Alzheimer's Disease (AD), and Type 2 Diabetes Mellitus (T2Dm); there are alternative hypotheses, now becoming increasingly evident, which suggest that the small biomolecules like redox noninnocent metals (Fe, Cu, Zn, etc.) and cofactors (Heme) have a definite influence in the onset and extent of such degenerative maladies. Dyshomeostasis of these components remains as one of the common features in both AD and T2Dm etiology. Recent advances in this course reveal that the metal/cofactor-peptide interactions and covalent binding can alarmingly enhance and modify the toxic reactivities, oxidize vital biomolecules, significantly contribute to the oxidative stress leading to cell apoptosis, and may precede the amyloid fibrils formation by altering their native folds. This perspective highlights this aspect of amyloidogenic pathology which revolves around the impact of the metals and cofactors in the pathogenic courses of AD and T2Dm including the active site environments, altered reactivities, and the probable mechanisms involving some highly reactive intermediates as well. It also discusses some in vitro metal chelation or heme sequestration strategies which might serve as a possible remedy. These findings might open up a new paradigm in our conventional understanding of amyloidogenic diseases. Moreover, the interaction of the active sites with small molecules elucidates potential biochemical reactivities that can inspire designing of drug candidates for such pathologies.
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Affiliation(s)
- Ishita Pal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick
Road, Jadavpur, Kolkata 700032, India
| | - Somdatta Ghosh Dey
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick
Road, Jadavpur, Kolkata 700032, India
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4
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Zinc insulin hexamer loaded alginate zinc hydrogel: preparation, characterization and in vivo hypoglycemic ability. Eur J Pharm Biopharm 2022; 179:173-181. [PMID: 36087882 DOI: 10.1016/j.ejpb.2022.08.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 08/22/2022] [Accepted: 08/27/2022] [Indexed: 11/21/2022]
Abstract
Alginate zinc hydrogel loaded with zinc insulin hexamer was prepared and characterized for oral insulin administration. The hydrogel was fabricated by dripping zinc insulin hexamer into sodium alginate solution and followed by crosslinking by zinc chloride. SEM image reveals the zinc insulin hexamer was integrated into the matrix of hydrogel. Zinc insulin hexamer loaded hydrogel shows no obvious cytotoxicity to both HT29 and Caco-2 cells. The developed hydrogel retards the burst release of insulin in simulated gastric fluid but promotes the release when in simulated intestinal fluid. In the diabetic mice, zinc insulin hexamer loaded alginate hydrogel demonstrates significant and prolonged hypoglycemic effect.
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Gülfen M, Özdemir A. Monitoring Cu(II)-insulin and Mn(II)-insulin complexes using potentiometric, chromatographic, UV–vis absorption and fluorescence emission spectroscopic techniques. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.132763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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6
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Structural view of insulin adsorption on the multiple sizes of Cu nanoparticles; molecular dynamics simulation study. Arch Biochem Biophys 2022; 722:109219. [DOI: 10.1016/j.abb.2022.109219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 04/08/2022] [Accepted: 04/09/2022] [Indexed: 11/19/2022]
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Arya S, Gourley AJ, Penedo JC, Blindauer CA, Stewart AJ. Fatty acids may influence insulin dynamics through modulation of albumin-Zn 2+ interactions. Bioessays 2021; 43:e2100172. [PMID: 34725844 DOI: 10.1002/bies.202100172] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 01/02/2023]
Abstract
Insulin is stored within the pancreas in an inactive Zn2+ -bound hexameric form prior to release. Similarly, clinical insulins contain Zn2+ and form multimeric complexes. Upon release from the pancreas or upon injection, insulin only becomes active once Zn2+ disengages from the complex. In plasma and other extracellular fluids, the majority of Zn2+ is bound to human serum albumin (HSA), which plays a vital role in controlling insulin pharmacodynamics by enabling removal of Zn2+ . The Zn2+ -binding properties of HSA are attenuated by non-esterified fatty acids (NEFAs) also transported by HSA. Elevated NEFA concentrations are associated with obesity and type 2 diabetes. Here we present the hypothesis that higher NEFA levels in obese and/or diabetic individuals may contribute to insulin resistance and affect therapeutic insulin dose-response profiles, through modulation of HSA/Zn2+ dynamics. We envisage this novel concept to have important implications for personalized treatments and management of diabetes-related conditions in the future.
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Affiliation(s)
- Swati Arya
- School of Medicine, University of St. Andrews, St. Andrews, Fife, UK
| | - Adam J Gourley
- School of Medicine, University of St. Andrews, St. Andrews, Fife, UK
| | - J Carlos Penedo
- Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews, Fife, UK
| | | | - Alan J Stewart
- School of Medicine, University of St. Andrews, St. Andrews, Fife, UK
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8
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Czubinski J. Fluorescence polarization as an approach to study the molecular interaction between lupin seed γ-conglutin and insulin. FOOD BIOSCI 2021. [DOI: 10.1016/j.fbio.2021.101073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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9
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Roy M, Pal I, Dey C, Dey A, Dey SG. Electronic structure and reactivity of heme bound insulin. J PORPHYR PHTHALOCYA 2021. [DOI: 10.1142/s1088424621500346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Insulin resistance as well as insulin deficiency are said to be principal to the development of type 2 diabetes mellitus (T2Dm). Heme has also been suggested to play an important role in the disease etiology since many of the heme deficiency symptoms constitute the common pathological features of T2Dm. Besides, iron overload, higher heme iron intake and transfusion requiring diseases are associated with a higher risk of T2Dm development. In this study the interaction between these two key components i.e. heme and insulin has been studied spectroscopically under different conditions which include the effect of excess peptide as well as increasing pH. The resultant heme-insulin complexes in their reduced state are found to produce very little partially reduced oxygen species (PROS) on getting oxidized by molecular oxygen. The interaction between insulin and previously reported T2Dm relevant heme-amylin complex were also examined using absorption and resonance Raman spectroscopy. The corresponding data suggest that insulin sequesters heme from heme-amylin to form the much less cytotoxic heme-insulin.
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Affiliation(s)
- Madhuparna Roy
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Ishita Pal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Chinmay Dey
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Abhishek Dey
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Somdatta Ghosh Dey
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
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10
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Kocyła A, Tran JB, Krężel A. Galvanization of Protein-Protein Interactions in a Dynamic Zinc Interactome. Trends Biochem Sci 2020; 46:64-79. [PMID: 32958327 DOI: 10.1016/j.tibs.2020.08.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 08/10/2020] [Accepted: 08/19/2020] [Indexed: 02/06/2023]
Abstract
The presence of Zn2+ at protein-protein interfaces modulates complex function, stability, and introduces structural flexibility/complexity, chemical selectivity, and reversibility driven in a Zn2+-dependent manner. Recent studies have demonstrated that dynamically changing Zn2+ affects numerous cellular processes, including protein-protein communication and protein complex assembly. How Zn2+-involved protein-protein interactions (ZPPIs) are formed and dissociate and how their stability and reactivity are driven in a zinc interactome remain poorly understood, mostly due to experimental obstacles. Here, we review recent research advances on the role of Zn2+ in the formation of interprotein sites, their architecture, function, and stability. Moreover, we underline the importance of zinc networks in intersystemic communication and highlight bioinformatic and experimental challenges required for the identification and investigation of ZPPIs.
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Affiliation(s)
- Anna Kocyła
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Józef Ba Tran
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Artur Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland.
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11
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Kotuniak R, Fra̧czyk T, Skrobecki P, Płonka D, Bal W. Gly-His-Thr-Asp-Amide, an Insulin-Activating Peptide from the Human Pancreas Is a Strong Cu(II) but a Weak Zn(II) Chelator. Inorg Chem 2018; 57:15507-15516. [DOI: 10.1021/acs.inorgchem.8b02841] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Radosław Kotuniak
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Tomasz Fra̧czyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
- Department of Immunology, Transplantology and Internal Medicine, Medical University of Warsaw, Nowogrodzka 59, 02-006 Warsaw, Poland
| | - Piotr Skrobecki
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Dawid Płonka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Wojciech Bal
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
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12
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Scudeller LA, Mavropoulos E, Tanaka MN, Costa AM, Braga CA, López EO, Mello A, Rossi AM. Effects on insulin adsorption due to zinc and strontium substitution in hydroxyapatite. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2017. [DOI: 10.1016/j.msec.2017.05.061] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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13
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Maret W. Zinc in Pancreatic Islet Biology, Insulin Sensitivity, and Diabetes. Prev Nutr Food Sci 2017; 22:1-8. [PMID: 28401081 PMCID: PMC5383135 DOI: 10.3746/pnf.2017.22.1.1] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 02/23/2017] [Indexed: 12/14/2022] Open
Abstract
About 20 chemical elements are nutritionally essential for humans with defined molecular functions. Several essential and nonessential biometals are either functional nutrients with antidiabetic actions or can be diabetogenic. A key question remains whether changes in the metabolism of biometals and biominerals are a consequence of diabetes or are involved in its etiology. Exploration of the roles of zinc (Zn) in this regard is most revealing because 80 years of scientific discoveries link zinc and diabetes. In pancreatic β- and α-cells, zinc has specific functions in the biochemistry of insulin and glucagon. When zinc ions are secreted during vesicular exocytosis, they have autocrine, paracrine, and endocrine roles. The membrane protein ZnT8 transports zinc ions into the insulin and glucagon granules. ZnT8 has a risk allele that predisposes the majority of humans to developing diabetes. In target tissues, increased availability of zinc enhances the insulin response by inhibiting protein tyrosine phosphatase 1B, which controls the phosphorylation state of the insulin receptor and hence downstream signalling. Inherited diseases of zinc metabolism, environmental exposures that interfere with the control of cellular zinc homeostasis, and nutritional or conditioned zinc deficiency influence the patho-biochemistry of diabetes. Accepting the view that zinc is one of the many factors in multiple gene-environment interactions that cause the functional demise of β-cells generates an immense potential for treating and perhaps preventing diabetes. Personalized nutrition, bioactive food, and pharmaceuticals targeting the control of cellular zinc in precision medicine are among the possible interventions.
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Affiliation(s)
- Wolfgang Maret
- Division of Diabetes and Nutritional Sciences, Faculty of Life Sciences and Medicine, King's College London, London SE1 9NH, UK
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Atabay M, Jahanbin Sardroodi J, Rastkar Ebrahimzadeh A. Adsorption and immobilisation of human insulin on graphene monoxide, silicon carbide and boron nitride nanosheets investigated by molecular dynamics simulation. MOLECULAR SIMULATION 2017. [DOI: 10.1080/08927022.2016.1270452] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Maryam Atabay
- Molecular Simulation Lab, Azarbaijan Shahid Madani University, Tabriz, Iran
- Department of Chemistry, Azarbaijan Shahid Madani University, Tabriz, Iran
| | - Jaber Jahanbin Sardroodi
- Molecular Simulation Lab, Azarbaijan Shahid Madani University, Tabriz, Iran
- Department of Chemistry, Azarbaijan Shahid Madani University, Tabriz, Iran
| | - Alireza Rastkar Ebrahimzadeh
- Department of Chemistry, Azarbaijan Shahid Madani University, Tabriz, Iran
- Department of Physics, Azarbaijan Shahid Madani University, Tabriz, Iran
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15
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Krężel A, Maret W. The biological inorganic chemistry of zinc ions. Arch Biochem Biophys 2016; 611:3-19. [PMID: 27117234 PMCID: PMC5120989 DOI: 10.1016/j.abb.2016.04.010] [Citation(s) in RCA: 380] [Impact Index Per Article: 47.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/14/2016] [Accepted: 04/20/2016] [Indexed: 12/21/2022]
Abstract
The solution and complexation chemistry of zinc ions is the basis for zinc biology. In living organisms, zinc is redox-inert and has only one valence state: Zn(II). Its coordination environment in proteins is limited by oxygen, nitrogen, and sulfur donors from the side chains of a few amino acids. In an estimated 10% of all human proteins, zinc has a catalytic or structural function and remains bound during the lifetime of the protein. However, in other proteins zinc ions bind reversibly with dissociation and association rates commensurate with the requirements in regulation, transport, transfer, sensing, signalling, and storage. In contrast to the extensive knowledge about zinc proteins, the coordination chemistry of the “mobile” zinc ions in these processes, i.e. when not bound to proteins, is virtually unexplored and the mechanisms of ligand exchange are poorly understood. Knowledge of the biological inorganic chemistry of zinc ions is essential for understanding its cellular biology and for designing complexes that deliver zinc to proteins and chelating agents that remove zinc from proteins, for detecting zinc ion species by qualitative and quantitative analysis, and for proper planning and execution of experiments involving zinc ions and nanoparticles such as zinc oxide (ZnO). In most investigations, reference is made to zinc or Zn2+ without full appreciation of how biological zinc ions are buffered and how the d-block cation Zn2+ differs from s-block cations such as Ca2+ with regard to significantly higher affinity for ligands, preference for the donor atoms of ligands, and coordination dynamics. Zinc needs to be tightly controlled. The interaction with low molecular weight ligands such as water and inorganic and organic anions is highly relevant to its biology but in contrast to its coordination in proteins has not been discussed in the biochemical literature. From the discussion in this article, it is becoming evident that zinc ion speciation is important in zinc biochemistry and for biological recognition as a variety of low molecular weight zinc complexes have already been implicated in biological processes, e.g. with ATP, glutathione, citrate, ethylenediaminedisuccinic acid, nicotianamine, or bacillithiol. Zinc ions not bound to proteins have critical roles in cell biology. Zinc has a unique coordination chemistry, poorly appreciated in the biosciences. Its coordination chemistry is significantly different from that of calcium ions. Specific conditions apply for buffering cellular zinc ions. Investigations with zinc need to consider solution chemistry and metal buffering.
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Affiliation(s)
- Artur Krężel
- Laboratory of Chemical Biology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14A, 50-383 Wroclaw, Poland.
| | - Wolfgang Maret
- King's College London, Metal Metabolism Group, Division of Diabetes and Nutritional Sciences, Department of Biochemistry, Faculty of Life Sciences of Medicine, 150 Stamford Street, London, SE1 9NH, UK.
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Zinc-induced oligomerization of zinc α2 glycoprotein reveals multiple fatty acid-binding sites. Biochem J 2015; 473:43-54. [PMID: 26487699 DOI: 10.1042/bj20150836] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/20/2015] [Indexed: 02/07/2023]
Abstract
Zinc α2 glycoprotein (ZAG) is an adipokine with a class I MHC protein fold and is associated with obesity and diabetes. Although its intrinsic ligand remains unknown, ZAG binds the dansylated C11 fatty acid 11-(dansylamino)undecanoic acid (DAUDA) in the groove between the α1 and α2 domains. The surface of ZAG has approximately 15 weak zinc-binding sites deemed responsible for precipitation from human plasma. In the present study the functional significance of these metal sites was investigated. Analytical ultracentrifugation (AUC) and CD showed that zinc, but not other divalent metals, causes ZAG to oligomerize in solution. Thus ZAG dimers and trimers were observed in the presence of 1 and 2 mM zinc. Molecular modelling of X-ray scattering curves and sedimentation coefficients indicated a progressive stacking of ZAG monomers, suggesting that the ZAG groove may be occluded in these. Using fluorescence-detected sedimentation velocity, these ZAG-zinc oligomers were again observed in the presence of the fluorescent boron dipyrromethene fatty acid C16-BODIPY (4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-hexadecanoic acid). Fluorescence spectroscopy confirmed that ZAG binds C16-BODIPY. ZAG binding to C16-BODIPY, but not to DAUDA, was reduced by increased zinc concentrations. We conclude that the lipid-binding groove in ZAG contains at least two distinct fatty acid-binding sites for DAUDA and C16-BODIPY, similar to the multiple lipid binding seen in the structurally related immune protein CD1c. In addition, because high concentrations of zinc occur in the pancreas, the perturbation of these multiple lipid-binding sites by zinc may be significant in Type 2 diabetes where dysregulation of ZAG and zinc homoeostasis occurs.
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Moore WT, Bowser SM, Fausnacht DW, Staley LL, Suh KS, Liu D. Beta Cell Function and the Nutritional State: Dietary Factors that Influence Insulin Secretion. Curr Diab Rep 2015; 15:76. [PMID: 26294335 DOI: 10.1007/s11892-015-0650-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Approximately 366 million people worldwide have been diagnosed with type-2 diabetes (T2D). Chronic insulin resistance, decreased functional β-cell mass, and elevated blood glucose are defining characteristics of T2D. Great advances have been made in understanding the pathogenesis of T2D with respect to the effects of dietary macronutrient composition and energy intake on β-cell physiology and glucose homeostasis. It has been further established that obesity is a leading pathogenic factor for developing insulin resistance. However, insulin resistance may not progress to T2D unless β-cells are unable to secret an adequate amount of insulin to compensate for decreased insulin sensitivity. Therefore, pancreatic β-cell dysfunction plays an important role in the development of overt diabetes. This paper reviews recent research findings on the effects of several micronutrients (zinc, vitamin D, iron, vitamin A), leucine, and the phytochemical, genistein on pancreatic β-cell physiology with emphasis on their effects on insulin secretion, specifically in the context of T2D.
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Affiliation(s)
- William T Moore
- Department of Human Nutrition, Foods and Exercises, College of Agricultural and Life Sciences, Virginia Tech Corporate Research Center, 1981 Kraft Drive, Blacksburg, VA, 24061, USA
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