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Eisner D, Neher E, Taschenberger H, Smith G. Physiology of intracellular calcium buffering. Physiol Rev 2023; 103:2767-2845. [PMID: 37326298 DOI: 10.1152/physrev.00042.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/08/2023] [Accepted: 06/11/2023] [Indexed: 06/17/2023] Open
Abstract
Calcium signaling underlies much of physiology. Almost all the Ca2+ in the cytoplasm is bound to buffers, with typically only ∼1% being freely ionized at resting levels in most cells. Physiological Ca2+ buffers include small molecules and proteins, and experimentally Ca2+ indicators will also buffer calcium. The chemistry of interactions between Ca2+ and buffers determines the extent and speed of Ca2+ binding. The physiological effects of Ca2+ buffers are determined by the kinetics with which they bind Ca2+ and their mobility within the cell. The degree of buffering depends on factors such as the affinity for Ca2+, the Ca2+ concentration, and whether Ca2+ ions bind cooperatively. Buffering affects both the amplitude and time course of cytoplasmic Ca2+ signals as well as changes of Ca2+ concentration in organelles. It can also facilitate Ca2+ diffusion inside the cell. Ca2+ buffering affects synaptic transmission, muscle contraction, Ca2+ transport across epithelia, and the killing of bacteria. Saturation of buffers leads to synaptic facilitation and tetanic contraction in skeletal muscle and may play a role in inotropy in the heart. This review focuses on the link between buffer chemistry and function and how Ca2+ buffering affects normal physiology and the consequences of changes in disease. As well as summarizing what is known, we point out the many areas where further work is required.
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Affiliation(s)
- David Eisner
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Erwin Neher
- Membrane Biophysics Laboratory, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Godfrey Smith
- School of Cardiovascular and Metabolic Health, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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Case DR, Zubieta J, Gonzalez R, Doyle RP. Synthesis and Chemical and Biological Evaluation of a Glycine Tripeptide Chelate of Magnesium. Molecules 2021; 26:2419. [PMID: 33919285 PMCID: PMC8122334 DOI: 10.3390/molecules26092419] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/13/2021] [Accepted: 04/18/2021] [Indexed: 11/16/2022] Open
Abstract
Magnesium (Mg2+) plays a crucial role in over 80% of all metabolic functions. It is becoming increasingly apparent that magnesium deficiency (hypomagnesemia) may play an important role in chronic disease. To counteract magnesium deficiency, there is an unmet clinical need to develop new fully characterized, highly bioavailable, and substantially water-soluble magnesium supplements. To this end, triglycine (HG3), a tripeptide of the amino acid glycine, was chosen as a chelating ligand for magnesium, given its natural occurrence and water solubility, and entropically-driven metal binding. Herein, we discuss the synthesis, chemical and physical characterization, and cellular uptake of a magnesium triglycine chelate (MgG3), an octahedral complex with extraordinary water solubility and improved cellular uptake in CaCo-2 cells than select commonly used magnesium supplements.
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Affiliation(s)
- Derek R. Case
- Department of Chemistry, 111 College Place, Syracuse University, Syracuse, NY 13244, USA; (D.R.C.); (J.Z.)
| | - Jon Zubieta
- Department of Chemistry, 111 College Place, Syracuse University, Syracuse, NY 13244, USA; (D.R.C.); (J.Z.)
| | - Ren Gonzalez
- Balchem Corporation, 52 Sunrise Park Road, New Hampton, NY 10958, USA;
| | - Robert P. Doyle
- Department of Chemistry, 111 College Place, Syracuse University, Syracuse, NY 13244, USA; (D.R.C.); (J.Z.)
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On the Mg2+ binding site of the ε subunit from bacterial F-type ATP synthases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1101-12. [DOI: 10.1016/j.bbabio.2015.05.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 05/20/2015] [Accepted: 05/22/2015] [Indexed: 11/19/2022]
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Gunner MR, Amin M, Zhu X, Lu J. Molecular mechanisms for generating transmembrane proton gradients. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1827:892-913. [PMID: 23507617 PMCID: PMC3714358 DOI: 10.1016/j.bbabio.2013.03.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/28/2013] [Accepted: 03/01/2013] [Indexed: 01/02/2023]
Abstract
Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side.
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Affiliation(s)
- M R Gunner
- Department of Physics, City College of New York, New York, NY 10031, USA.
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Khairallah GN, Thum CCL, Lesage D, Tabet JC, O’Hair RAJ. Gas-Phase Formation and Fragmentation Reactions of the Organomagnesates [RMgX2]−. Organometallics 2013. [DOI: 10.1021/om3011917] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Denis Lesage
- Institut Parisien de Chimie Moléculaire, Université Pierre et Marie Curie-Paris 6 (UPMC), UMR 7201- FR2769, Place Jussieu, 75252 Paris Cedex 05, France
| | - Jean-Claude Tabet
- Institut Parisien de Chimie Moléculaire, Université Pierre et Marie Curie-Paris 6 (UPMC), UMR 7201- FR2769, Place Jussieu, 75252 Paris Cedex 05, France
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Dudev T, Lim C. Metal-Binding Affinity and Selectivity of Nonstandard Natural Amino Acid Residues from DFT/CDM Calculations. J Phys Chem B 2009; 113:11754-64. [DOI: 10.1021/jp904249s] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Todor Dudev
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan, and the Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Carmay Lim
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan, and the Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan
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Appell M, Dombrink-Kurtzman MA, Kendra DF. Comparative study of patulin, ascladiol, and neopatulin by density functional theory. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.theochem.2008.09.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Dudev T, Lim C. Metal binding affinity and selectivity in metalloproteins: insights from computational studies. Annu Rev Biophys 2008; 37:97-116. [PMID: 18573074 DOI: 10.1146/annurev.biophys.37.032807.125811] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This review highlights insights gained from computational studies on protein-metal recognition. We systematically dissect the various factors governing metal binding affinity and selectivity in proteins starting from (a) the intrinsic properties of the metal and neighboring metal cations (if present), to (b) the primary coordination sphere, (c) the second coordination shell, (d) the protein matrix, (e) the bulk solvent, and (f) competing non-protein ligands from the surrounding biological environment. The results herein reveal the fundamental principles and the molecular bases underlying protein-metal recognition, which serve as a guide to engineer novel metalloproteins with programmed properties.
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Affiliation(s)
- Todor Dudev
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.
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Rezabal E, Mercero JM, Lopez X, Ugalde JM. Protein side chains facilitate Mg/Al exchange in model protein binding sites. Chemphyschem 2008; 8:2119-24. [PMID: 17712827 DOI: 10.1002/cphc.200700335] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Among the most frequent protein binding sites served by Mg(II), we identify those which have higher affinity towards Al(III). We also estimate the free energies of metal exchange for all these binding sites taking into account solvent effects explicitly. The obtained results show that thermodynamically favored Mg(II)/Al(III) exchange reactions take place at a number of these metal binding sites, which could possibly be related to some dysfunctions of Mg(II)-dependent biological processes. Additionally, they shed light on the molecular basis of the toxicity of Al(III) in living organisms.
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Affiliation(s)
- Elixabete Rezabal
- Kimika Fakultatea, Euskal Herriko Unibertsitatea and Donostia International Physics Center, P. K. 1072, 20080 Donostia, Euskadi, Spain
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Xiang F, Cukier RI, Bu Y. Ca2+ selectivity of the sarcoplasmic reticulum Ca2+-ATPase at the enzyme-water interface and in the Ca2+ entrance channel. J Phys Chem B 2007; 111:12282-93. [PMID: 17914795 DOI: 10.1021/jp073883q] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The sarcoplasmic reticulum (SR) Ca(2+)-ATPase, a P-type transmembrane protein, can transport Ca(2+) from the cytoplasmic to the luminal side over other cations specifically. The proposed Ca(2+) entrance channel, composed of the main-chain carbonyl oxygen and side-chain carboxyl oxygen atoms of the amino acids, opens on the enzyme surface, just above the biphospholipid layer membrane-water interface, where Trp residues are frequently found. In this work, the physicochemical nature of Ca(2+) selectivity over Mg(2+) on the surface of the SR Ca(2+)-ATPase has been investigated using the density functional theory (DFT) method. The selection process can be regarded as the first step of the specificity of the enzyme to transport Ca(2+). Subsequently, the specificity of the entrance channel to conduct Ca(2+) over other cations has also been explored. As revealed by thermodynamic analyses, either the aromatic or the aliphatic amino acid residues distributed on the surface of Ca(2+)-ATPase have a bigger affinity to Mg(2+) than to Ca(2+), resulting in a concentration decrease of free Mg(2+) in the local region. Thus, Ca(2+) can transport into the Ca(2+)-entrance channel more easily. Whereafter, for a small quantity of Mg(2+) entering this channel accompanying the Ca(2+) current, the strong electrostatic interactions between Mg(2+) and the ligands will limit the activity of this metal ion, which facilitates the weakly bonded Ca(2+) passing through the channel at a relatively high rate, as suggested by the "sticky-pore" hypothesis. Furthermore, the corresponding theoretical investigations have demonstrated that the increase of the ligand electronegativity can enhance their discrimination between these two cations effectively.
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Affiliation(s)
- Feng Xiang
- Key Laboratory for Colloid and Interface Chemistry of Ministry of Education, The Modeling & Simulation Chemistry Division, Shandong University, Jinan 250100, P. R. China
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Rezabal E, Mercero JM, Lopez X, Ugalde JM. A theoretical study of the principles regulating the specificity for Al(III) against Mg(II) in protein cavities. J Inorg Biochem 2007; 101:1192-200. [PMID: 17659345 DOI: 10.1016/j.jinorgbio.2007.06.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Revised: 05/25/2007] [Accepted: 06/05/2007] [Indexed: 10/23/2022]
Abstract
Several toxic effects arise from Al's presence in living systems, one of them being the alteration of the natural role of enzymes and non-enzyme proteins. Al(III) is capable of entering protein active sites that in normal conditions should be occupied by other metals. Even if Mg(II) is an ubiquitous metal in biological systems, the interference of aluminium in magnesium metabolism is not clear yet. In this work, a systematic study of the affinity of Al(III) for different protein binding sites is presented, with special attention on structural parameters, the role of the charge and the presence of different ligands in the protein cavity. The specificity of the binding site for Al(III) against Mg(II) has been studied, and also the thermodynamical propensity of a Mg(II)/Al(III) exchange. Quantum mechanical methods that proved to be reliable in previous works have been used, namely, the density functional theory (DFT) and polarizable continuum model (PCM).
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Affiliation(s)
- Elixabete Rezabal
- Kimika Fakultatea, Euskal Herriko Unibertsitatea and Donostia International Physics Center, PK 1072, 20080 Donostia, Euskadi, Spain.
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