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Li P, Yang X, Chen F, Wang D, Hao D, Xu Z, Qiu M, He S, Xia F, Tian Y. Confined Water Dominates Ion/Molecule Transport in Hydrogel Nanochannels. NANO LETTERS 2024; 24:897-904. [PMID: 38193898 DOI: 10.1021/acs.nanolett.3c04107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Current artificial nanochannels rely more on charge interactions for intelligent mass transport. Nevertheless, popular charged nanochannels would lose their advantages in long-term applications. Confined water, an indispensable transport medium in biological nanochannels, dominating the transport process in the uncharged nanochannels perfectly provides a new perspective. Herein, we achieve confined-water-dominated mass transport in hydrogel nanochannels (HNCs) constructed by in situ photopolymerization of acrylic acid (PAA) hydrogel in anodic alumina (AAO) nanochannels. HNCs show selectivity to Na+ transport and a high transport rate of molecules after introducing Na+/Li+, compared with other alkali metal ions like Cs+/K+. The mechanism given by ATR-FTIR shows that the hydrogen-bonding structure of confined water in HNCs is destabilized by Na+/Li+, which facilitates mass transport, but is constrained by Cs+/K+, resulting in transport inhibition. This work elucidates the relationship between confined water and mass transport in uncharged nanochannels while also presenting a strategy for designing functional nanochannel devices.
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Affiliation(s)
- Peijia Li
- Laboratory of Bio-Inspired Materials and Interface Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Xiaotao Yang
- Laboratory of Bio-Inspired Materials and Interface Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Fengxiang Chen
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Hubei Key Laboratory of Digital Textile Equipment, Wuhan Textile University, Wuhan 430200, People's Republic of China
| | - Dianyu Wang
- School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, People's Republic of China
| | - Dezhao Hao
- Laboratory of Bio-Inspired Materials and Interface Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Zhe Xu
- Laboratory of Bio-Inspired Materials and Interface Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Ming Qiu
- Laboratory of Bio-Inspired Materials and Interface Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Shaofan He
- Laboratory of Bio-Inspired Materials and Interface Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Fan Xia
- State Key Laboratory of Biogeology and Environmental Geology, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430078, People's Republic of China
| | - Ye Tian
- Laboratory of Bio-Inspired Materials and Interface Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, People's Republic of China
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Manoj KM, Gideon DA, Bazhin NM, Tamagawa H, Nirusimhan V, Kavdia M, Jaeken L. Na,K-ATPase: A murzyme facilitating thermodynamic equilibriums at the membrane-interface. J Cell Physiol 2023; 238:109-136. [PMID: 36502470 DOI: 10.1002/jcp.30925] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/08/2022] [Accepted: 11/14/2022] [Indexed: 12/14/2022]
Abstract
The redox metabolic paradigm of murburn concept advocates that diffusible reactive species (DRS, particularly oxygen-centric radicals) are mainstays of physiology, and not mere pathological manifestations. The murburn purview of cellular function also integrates the essential principles of bioenergetics, thermogenesis, homeostasis, electrophysiology, and coherence. In this context, any enzyme that generates/modulates/utilizes/sustains DRS functionality is called a murzyme. We have demonstrated that several water-soluble (peroxidases, lactate dehydrogenase, hemogoblin, etc.) and membrane-embedded (Complexes I-V in mitochondria, Photosystems I/II in chloroplasts, rhodopsin/transducin in rod cells, etc.) proteins serve as murzymes. The membrane protein of Na,K-ATPase (NKA, also known as sodium-potassium pump) is the focus of this article, owing to its centrality in neuro-cardio-musculo electrophysiology. Herein, via a series of critical queries starting from the geometric/spatio-temporal considerations of diffusion/mass transfer of solutes in cells to an update on structural/distributional features of NKA in diverse cellular systems, and from various mechanistic aspects of ion-transport (thermodynamics, osmoregulation, evolutionary dictates, etc.) to assays/explanations of inhibitory principles like cardiotonic steroids (CTS), we first highlight some unresolved problems in the field. Thereafter, we propose and apply a minimalist murburn model of trans-membrane ion-differentiation by NKA to address the physiological inhibitory effects of trans-dermal peptide, lithium ion, volatile anesthetics, confirmed interfacial DRS + proton modulators like nitrophenolics and unsaturated fatty acid, and the diverse classes of molecules like CTS, arginine, oximes, etc. These explanations find a pan-systemic connectivity with the inhibitions/uncouplings of other membrane proteins in cells.
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Affiliation(s)
- Kelath Murali Manoj
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Shoranur-2, Kerala, India
| | - Daniel A Gideon
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Shoranur-2, Kerala, India
| | - Nikolai M Bazhin
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk, Russia
| | - Hirohisa Tamagawa
- Department of Mechanical Engineering, Gifu University, Gifu City, Japan
| | - Vijay Nirusimhan
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Shoranur-2, Kerala, India
| | - Mahendra Kavdia
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, USA
| | - Laurent Jaeken
- Department of Industrial Sciences and Technology, Karel de Grote-Hogeschool, Antwerp University Association, Antwerp, Belgium
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Krupskaya TV, Elagina NV, Borisenko NV, Turov VV. Features of the Hydration of Consolidated Methyl Silica and a Composite Based on It and Succinic Acid. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2019. [DOI: 10.1134/s0036024419070136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Turov VV. INFLUENCE OF ENVIRONMENT AND HYDROPHOBIC SILICA ON WATER BINDING IN COMPOSITES CONTAINING MILLED MEDICAL PLANTS. BIOTECHNOLOGIA ACTA 2018. [DOI: 10.15407/biotech11.06.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Turov VV, Goncharuk VV, Ogenko VM, Krupskaya TV, Tsapko MD. The isotope effect in formation of surface water clusters in heterogeneous systems. J WATER CHEM TECHNO+ 2015. [DOI: 10.3103/s1063455x1505001x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Jaeken L, Vasilievich Matveev V. Coherent Behavior and the Bound State of Water and K(+) Imply Another Model of Bioenergetics: Negative Entropy Instead of High-energy Bonds. Open Biochem J 2012; 6:139-59. [PMID: 23264833 PMCID: PMC3527877 DOI: 10.2174/1874091x01206010139] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 09/06/2012] [Accepted: 09/12/2012] [Indexed: 11/22/2022] Open
Abstract
Observations of coherent cellular behavior cannot be integrated into widely accepted membrane (pump) theory (MT) and its steady state energetics because of the thermal noise of assumed ordinary cell water and freely soluble cytoplasmic K(+). However, Ling disproved MT and proposed an alternative based on coherence, showing that rest (R) and action (A) are two different phases of protoplasm with different energy levels. The R-state is a coherent metastable low-entropy state as water and K(+) are bound to unfolded proteins. The A-state is the higher-entropy state because water and K(+) are free. The R-to-A phase transition is regarded as a mechanism to release energy for biological work, replacing the classical concept of high-energy bonds. Subsequent inactivation during the endergonic A-to-R phase transition needs an input of metabolic energy to restore the low entropy R-state. Matveev's native aggregation hypothesis allows to integrate the energetic details of globular proteins into this view.
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Affiliation(s)
- Laurent Jaeken
- Laboratory of Biochemistry, Karel de Grote University College, Department of Applied Engineering, Salesianenlaan 30, B-2660, Antwerp, Belgium
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Water in the orchestration of the cell machinery. Some misunderstandings: a short review. J Biol Phys 2011; 38:13-26. [PMID: 23277667 DOI: 10.1007/s10867-011-9225-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 04/13/2011] [Indexed: 10/18/2022] Open
Abstract
Nowadays, biologists can explore the cell at the nanometre level. They discover an unsuspected world, amazingly overcrowded, complex and heterogeneous, in which water, also, is complex and heterogeneous. In the cell, statistical phenomena, such as diffusion, long considered as the main transport for water soluble substances, must be henceforth considered as inoperative to orchestrate cell activity. Results at this level are not yet numerous enough to give an exact representation of the cell machinery; however, they are sufficient to cease reasoning in terms of statistics (diffusion, law of mass action, pH, etc.) and encourage cytologists and biochemists to prospect thoroughly the huge panoply of the biophysical properties of macromolecule-water associations at the nanometre level. Our main purpose, here, is to discuss some of the more common misinterpretations due to the ignorance of these properties, and expose briefly the bases for a better approach of the cell machinery. Giorgio Careri, who demonstrated the correlation between proton currents at the surface of lysozyme and activity of this enzyme was one of the pioneers of this approach.
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Wiggins PM, van Ryn RT. Changes in ionic selectivity with changes in density of water in gels and cells. Biophys J 2010; 58:585-96. [PMID: 19431765 DOI: 10.1016/s0006-3495(90)82402-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Gels equilibrated with aqueous solutions of impermeant solutes reached a steady state in which, in the absence of a pressure difference, the activity of water in the pores of the gel was higher than that of water in the external solution. The chemical potential of water in the gel/polymer solution slurry was higher than that in the supernatant polymer solution removed from the gel. Water in the pores of the gel decreased in density to 0.96 as increasing osmotic stress was applied. It is argued that at constant temperature and pressure water can equilibrate between two compartments of unequal osmolality only by adjusting its molar volume. Experiments showed that when gel water had a higher activity than external water it was K(+) selective; when it had a lower activity it was Na(+) selective. It is proposed that a continuous spectrum of water structures can exist in these two compartment systems from dense, reactive, weakly-bonded water which selects highly hydrated ions, to expanded, stretched, unreactive, viscous water which is strongly hydrogen bonded and selects K(+) and univalent anions. These findings are related to the state and properties of cytoplasmic water which is probably held under osmotic stress by the activity of the sodium pump.
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Affiliation(s)
- P M Wiggins
- Department of Medicine, School of Medicine, University of Auckland, Auckland, New Zealand
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Johansson B. Effects of functional water on heart rate, heart rate variability, and salivary immunoglobulin a in healthy humans: a pilot study. J Altern Complement Med 2009; 15:871-7. [PMID: 19678777 DOI: 10.1089/acm.2008.0336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE This study was designed to explore the effects of drinking an average dietary volume of functional water on blood pressure, short-term cardiovascular variables, and salivary immunoglobulin A. DESIGN Subjects were studied in a randomized pre-post crossover design the morning after an overnight fast. SUBJECTS Fifteen (15) healthy nonsmoking subjects, 8 males and 7 females, aged between 15 and 49 years, participated in the study. INTERVENTION Short-term (10 minute) electrocardiography was measured in the participants before and after drinking either control mineral or functional water. The measurements were randomized, double blinded, and held two weeks apart. Saliva was collected for 4 minutes before the start of each electrocardiograph measurement. Blood pressure was monitored at 5 minute intervals for one hour as the mean of triplicate consecutive measurements. RESULTS Drinking 100 mL of control mineral or functional water did not alter arterial blood pressure in the 60 minutes post-drinking. Drinking control mineral water led to a significant fall in the heart rate, although all time domain and power density parameters remained unaffected. Consumption of functional water resulted in a significant difference in all time domain measures and in three of the power density parameters. The heart rate fell, while RR interbeat intervals, standard deviation of the normal-to-normal heartbeats (SDNN), and the square root of the mean squared differences of successive NN intervals (RMSSD) increased. A large rise in low (LF) and high frequency (HF) power had a significant effect on total power, indicating homeodynamic balance. Elevated LF power indicated intensified spectral power at frequencies in the range of 0.1 Hz, thus improving autonomic stability. The effect on the heart rate may confirm changes in cellular metabolism. Parasympathetic pathway activation stimulated secretory immunoglobulin A on mucosal surfaces, which protects against pathogenic invasion. CONCLUSIONS The drinking of functional water in healthy subjects elicited a rapid parasympathetic restorative response from the heart as well as stimulating mucosal humoral immunity. Functional water acts as an unconditional natural stimulus that elicits an involuntary response and facilitates physiological homeostasis.
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Affiliation(s)
- Charmian J. O'connor
- Department of Chemistry, University of Auckland, Private Bag, Auckland, New Zealand
| | - Philippa M. Wiggins
- Department of Medicine, University of Auckland School of Medicine, Auckland, New Zealand
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Johansson B. Heart Rate and Heart Rate Variability Response to the Transpiration of Vortex-Water byBegonia EliatorPlants to the Air in an Office During Visual Display Terminal Work. J Altern Complement Med 2008; 14:993-1003. [DOI: 10.1089/acm.2007.0525] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Abstract
Background Many well-documented biochemical processes lack a molecular mechanism. Examples are: how ATP hydrolysis and an enzyme contrive to perform work, such as active transport; how peptides are formed from amino acids and DNA from nucleotides; how proteases cleave peptide bonds, how bone mineralises; how enzymes distinguish between sodium and potassium; how chirality of biopolymers was established prebiotically. Methodology/Principal Findings It is shown that involvement of water in all these processes is mandatory, but the water must be of the simplified configuration in which there are only two strengths of water-water hydrogen bonds, and in which these two types of water coexist as microdomains throughout the liquid temperature range. Since they have different strengths of hydrogen bonds, the microdomains differ in all their physical and chemical properties. Solutes partition asymmetrically, generating osmotic pressure gradients which must be compensated for or abolished. Displacement of the equilibrium between high and low density waters incurs a thermodynamic cost which limits solubility, depresses ionisation of water, drives protein folding and prevents high density water from boiling at its intrinsic boiling point which appears to be below 0°C. Active processes in biochemistry take place in sequential partial reactions, most of which release small amounts of free energy as heat. This ensures that the system is never far from equilibrium so that efficiency is extremely high. Energy transduction is neither possible and nor necessary. Chirality was probably established in prebiotic clays which must have carried stable populations of high density and low density water domains. Bioactive enantiomorphs partition into low density water in which they polymerise spontaneously. Conclusions/Significance The simplified model of water has great explanatory power.
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Mentré P, Hui Bon Hoa G. Effects of high hydrostatic pressures on living cells: a consequence of the properties of macromolecules and macromolecule-associated water. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 201:1-84. [PMID: 11057830 DOI: 10.1016/s0074-7696(01)01001-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Sixty percent of the Earth's biomass is found in the sea, at depths greater than 1000 m, i.e., at hydrostatic pressures higher than 100 atm. Still more surprising is the fact that living cells can reversibly withstand pressure shifts of 1000 atm. One explanation lies in the properties of cellular water. Water forms a very thin film around macromolecules, with a heterogeneous structure that is an image of the heterogeneity of the macromolecular surface. The density of water in contact with macromolecules reflects the physical properties of their different domains. Therefore, any macromolecular shape variations involving the reorganization of water and concomitant density changes are sensitive to pressure (Le Chatelier's principle). Most of the pressure-induced changes to macromolecules are reversible up to 2000 atm. Both the effects of pressure shifts on living cells and the characteristics of pressure-adapted species are opening new perspectives on fundamental problems such as regulation and adaptation.
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Affiliation(s)
- P Mentré
- Station INRA 806, Institut de Biologie Physico-Chimique, Paris, France
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Abstract
Although we have a rather elaborate "working-cycle" for the 60 kDa molecular chaperones, which possess a cavity, and are called Anfinsen-cage-type chaperones to emphasize that they provide a closed, protected environment to help the folding of their substrates, our understanding of the molecular mechanism of how these chaperones help protein folding is still incomplete. The present study adds two novel elements to the mechanism of how Anfinsen-cage-type chaperones (members of the 60 kDa chaperone family) aid protein folding. It is proposed that (1) these chaperones do not generally unfold their targets, but by a multidirectional expansion preferentially loosen the tight, inner structure of the collapsed target protein; and (2) during the expansion water molecules enter the hydrophobic core of the target, this percolation being a key step in chaperone action. This study compares this chaperone-percolator model with existing explanations and suggests further experiments to test it. BioEssays 1999;21:959-965.
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Affiliation(s)
- P Csermely
- Department of Medical Chemistry, Semmelweis University, H-1444 Budapest, P.O. Box 260, Hungary.
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Affiliation(s)
- P M Wiggins
- Department of Medicine, School of Medicine, University of Auckland, New Zealand
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Muller AW. Were the first organisms heat engines? A new model for biogenesis and the early evolution of biological energy conversion. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1995; 63:193-231. [PMID: 7542789 DOI: 10.1016/0079-6107(95)00004-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- A W Muller
- E.C. Slater Institute, BioCentrum Amsterdam, Universiteit van Amsterdam, The Netherlands
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Plesner IW, Malmgren-Hansen B, Sørensen TS. Distribution of electrolytes between membraneous and bulk phases, and the dielectric properties of membraneous water, studied by impedance spectroscopy measurements on dense cellulose acetate membranes. ACTA ACUST UNITED AC 1994. [DOI: 10.1039/ft9949002381] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Fontes CF, Barrabin H, Scofano HM, Nørby JG. The role of Mg2+ and K+ in the phosphorylation of Na+,K(+)-ATPase by ATP in the presence of dimethylsulfoxide but in the absence of Na+. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1104:215-25. [PMID: 1312864 DOI: 10.1016/0005-2736(92)90153-d] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We have previously demonstrated that Na+,K(+)-ATPase can be phosphorylated by 100 microM ATP and 5 mM Mg2+ and in the absence of Na+, provided that 40% dimethylsulfoxide (Me2SO) is present. Phosphorylation was stimulated by K+ up to a steady-state level of about 50% of Etot (Barrabin et al. (1990) Biochim. Biophys. Acta 1023, 266-273). Here we describe the time-course of phosphointermediate (EP) formation and of dephosphorylation of EP at concentrations of Mg2+ from 0.1 to 5000 microM and of K+ from 0.01 to 100 mM. The results were simulated by a simplified version of the commonly accepted Albers-Post model, i.e. a 3-step reaction scheme with a phosphorylation, a dephosphorylation and an isomerization/deocclusion step. Furthermore it was necessary to include an a priori, Mg(2+)- and K(+)-independent, equilibration between two enzyme forms, only one of which (constituting 14% of Etot) reacted directly with ATP. The role of Mg(2+) was two-fold: At low Mg2+, phosphorylation was stimulated by Mg2+ due to formation of the substrate MgATP, whereas at higher concentrations it acted as an inhibitor at all three steps. The affinity for the inhibitory Mg(2+)-binding was increased several-fold, relative to that in aqueous media, by dimethylsulfoxide. K+ stimulated dephosphorylation at all Mg(2+)-concentrations, but at high, inhibitory [Mg2+], K+ also stimulated the phosphorylation reaction, increasing both the rate coefficient and the steady-state level of EP. Generally, the presence of Me2SO seems to inhibit the dephosphorylation step, the isomerization/deocclusion step, and to a lesser extent (if at all) the phosphorylation reaction, and we discuss whether this reflects that Me2SO stabilizes occluded conformations of the enzyme even in the absence of monovalent cations. The results confirm and elucidate the stimulating effect of K+ on EP formation from ATP in the absence of Na+, but they leave open the question of the molecular mechanism by which Me2SO, inhibitory Mg2+ and stimulating K+ interact with the Na+,K(+)-ATPase.
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Affiliation(s)
- C F Fontes
- Departamento de Bioquímica, ICB, CCS, Universidade Federal do Rio de Janeiro, Brasil
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Affiliation(s)
- J A Rupley
- Department of Biochemistry, University of Arizona, Tucson 85716
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The Interactions of Water and Proteins in Cellular Function. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1991. [DOI: 10.1007/978-3-642-76553-7_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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CLEGG J, DROST-HANSEN W. On the biochemistry and cell physiology of water. PHYLOGENETIC AND BIOCHEMICAL PERSPECTIVES 1991. [DOI: 10.1016/b978-0-444-89124-2.50005-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Abstract
The state of intracellular water has been a matter of controversy for a long time for two reasons. First, experiments have often given conflicting results. Second, hitherto, there have been no plausible grounds for assuming that intracellular water should be significantly different from bulk water. A collective behavior of water molecules is suggested here as a thermodynamically inevitable mechanism for generation of appreciable zones of abnormal water. At a highly charged surface, water molecules move together, generating a zone of water perhaps 6 nm thick, which is weakly hydrogen bonded, fluid, and reactive and selectively accumulates small cations, multivalent anions, and hydrophobic solutes. At a hydrophobic surface, molecules move apart and local water becomes strongly bonded, inert, and viscous and accumulates large cations, univalent anions, and compatible solutes. Proteins and many other biopolymers have patchy surfaces which therefore induce, by the two mechanisms described, patchy interfacial water structures, which extended appreciable distances from the surface. The reason for many conflicting experimental results now becomes apparent. Average values of properties of water measured in gels, cells, or solutions of proteins are often not very different from the same properties of normal water, giving no indication that they are averages of extreme values. To detect the operation of this phenomenon, it is necessary to probe selectively a single abnormal population. Examples of such experiments are given. It is shown that this collective behavior of water molecules amounts to a considerable biological force, which can be equivalent to a pressure of 1,000 atm (1.013 x 10(5) kPa). It is suggested that cells selectively accumulate K+ ions and compatible solutes to avoid extremes of water structure in their aqueous compartments, but that cation pumps and other enzymes exploit the different solvent properties and reactivities of water to perform work of transport or synthesis.
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Affiliation(s)
- P M Wiggins
- Department of Medicine, University of Auckland School of Medicine, New Zealand
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