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Coleman JE, Gettins P. Alkaline phosphatase, solution structure, and mechanism. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 55:381-452. [PMID: 6312783 DOI: 10.1002/9780470123010.ch5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Murphy JE, Stec B, Ma L, Kantrowitz ER. Trapping and visualization of a covalent enzyme-phosphate intermediate. NATURE STRUCTURAL BIOLOGY 1997; 4:618-22. [PMID: 9253408 DOI: 10.1038/nsb0897-618] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Using a mutant version of E. coli alkaline phosphatase, we succeeded in trapping and determining the structure of the phospho-enzyme intermediate. The X-ray structure also revealed the catalytic water molecule, bound to one of the active site zinc ions, positioned ideally for the apical attack necessary for the hydrolysis of the intermediate.
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Alcantara A, Sinisterra J, Guanti G, Thea S, Williams A. Importance of Hansch's π parameter in the catalytic action of microgel-immobilised subtilisin dissolved in tetrahydrofuran solvent. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/0304-5102(93)87116-p] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Xu X, Kantrowitz E. The importance of aspartate 327 for catalysis and zinc binding in Escherichia coli alkaline phosphatase. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41992-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Zhang ZY, Van Etten RL. Leaving group dependence and proton inventory studies of the phosphorylation of a cytoplasmic phosphotyrosyl protein phosphatase from bovine heart. Biochemistry 1991; 30:8954-9. [PMID: 1654080 DOI: 10.1021/bi00101a006] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The kcat and Km values for the bovine heart low molecular weight phosphotyrosyl protein phosphatase catalyzed hydrolysis of 16 aryl phosphate monoesters and of five alkyl phosphate monoesters having the structure Ar(CH2)nOPO3H2 (n = 1-5) were measured at pH 5.0 and 37 degrees C. With the exception of alpha-naphthyl phosphate and 2-chlorophenyl phosphate, which are subject to steric effects, the values of kcat are effectively constant for the aryl phosphate monoesters. This is consistent with the catalysis being nucleophilic in nature, with the existence of a common covalent phosphoenzyme intermediate, and with the breakdown of this intermediate being rate-limiting. In contrast, kcat for the alkyl phosphate monoesters is much smaller and the rate-limiting step for these substrates is interpreted to be the phosphorylation of the enzyme. A single linear correlation is observed for a plot of log (kcat/Km) vs leaving group pKa for both classes of substrates at pH 5.0: log (kcat/Km) = -0.28pKa + 6.88 (n = 19, r = 0.89), indicating a uniform catalytic mechanism for the phosphorylation event. The small change in effective charge (-0.28) on the departing oxygen of the substrate is similar to that observed in the specific acid catalyzed hydrolysis of monophosphate monoanions (-0.27) and is consistent with a strong electrophilic interaction of the enzyme with this oxygen atom in the transition state. The D2O solvent isotope effect and proton inventory experiments indicate that only one proton is "in flight" in the transition state of the phosphorylation process and that this proton transfer is responsible for the reduction of effective charge on the leaving oxygen.
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Affiliation(s)
- Z Y Zhang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-1393
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Xu X, Kantrowitz ER. A water-mediated salt link in the catalytic site of Escherichia coli alkaline phosphatase may influence activity. Biochemistry 1991; 30:7789-96. [PMID: 1907846 DOI: 10.1021/bi00245a018] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Escherichia coli alkaline phosphatase catalyzes the hydrolysis of a wide variety of phosphomonoesters at similar rates, and the reaction proceeds through a phosphoenzyme intermediate. The active site region is highly conserved between the E. coli and mammalian alkaline phosphatases. The three-dimensional structure of the E. coli enzyme indicates that Lys-328, which is replaced by histidine in all mammalian alkaline phosphatases, is bridged to the phosphate through a water molecule. This water molecule is also hydrogen bonded to Asp-327, a bidendate ligand of the one of the two zinc atoms. Here we report the use of site-specific mutagenesis to convert Lys-328 to both histidine and alanine. Steady-state kinetic studies above pH 7.0 indicate that both mutant enzymes have altered pH versus activity profiles compared to the profile for the wild-type enzyme. At pH 10.3, in the presence of Tris, the Lys-328----Ala enzyme is approximately 14-fold more active than the wild-type enzyme. At the same pH in the absence of Tris the Lys-328----Ala enzyme is still 6-fold more active than the wild-type enzyme. Both mutant enzymes have lower phosphate affinities than the wild-type enzyme at all pH values investigated. Pre-steady-state kinetics at pH 5.5 reveal that the Lys-328----Ala enzyme behaves very similar to the phosphate-free wild-type enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- X Xu
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02167
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Butler-Ransohoff JE, Kendall DA, Freeman S, Knowles JR, Kaiser ET. Stereochemistry of phospho group transfer catalyzed by a mutant alkaline phosphatase. Biochemistry 1988; 27:4777-80. [PMID: 3048390 DOI: 10.1021/bi00413a029] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The stereochemical course of the phospho group transfer catalyzed by mutant (S102C) alkaline phosphatase from Escherichia coli was investigated by using 31P nuclear magnetic resonance spectroscopy. Transphosphorylation from 4-nitrophenyl (Rp)-[16O, 17O, 18O]phosphate to (S)-propane-1,2-diol occurs with overall retention of configuration at phosphorus. This result is consistent with the view that the hydrolysis of substrates by this mutant enzyme proceeds by way of a covalent phosphoenzyme intermediate in the same manner as the wild-type alkaline phosphatase.
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Affiliation(s)
- J E Butler-Ransohoff
- Laboratory of Bioorganic Chemistry and Biochemistry, Rockefeller University, New York, New York 10021
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Butler-Ransohoff JE, Kendall DA, Kaiser ET. Use of site-directed mutagenesis to elucidate the role of arginine-166 in the catalytic mechanism of alkaline phosphatase. Proc Natl Acad Sci U S A 1988; 85:4276-8. [PMID: 3288990 PMCID: PMC280410 DOI: 10.1073/pnas.85.12.4276] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The guanidinium group of arginine-166 has been postulated to act as an electrophilic species during phosphorylation of alkaline phosphatase. Its role could be either to stabilize the developing negative charge on the oxygen of the leaving group or the pentacoordinate transition state or to help bind the -PO2-3 group. We have produced via site-directed mutagenesis two Escherichia coli alkaline phosphatase mutants (lysine-166 and glutamine-166) to test whether the guanidinium group plays a critical role in catalysis. Comparative kinetic characterization of the lysine-166 and glutamine-166 mutants indicates that the charge at residue 166 is not required for the hydrolysis of phosphate monoesters. Small decreases in kcat are observed for both the lysine and glutamine mutants, relative to the wild-type enzyme, but the value for the uncharged glutamine mutant is only one-third that of lysine. Thus, the stabilizing effect of the positively charged guanidinium group does not appear to play a major role in the rate-limiting step for substrate hydrolysis. A significant effect on the Km value is seen only for the glutamine mutant.
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Affiliation(s)
- J E Butler-Ransohoff
- Laboratory of Bioorganic Chemistry and Biochemistry, Rockefeller University, New York, NY 10021-6399
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Malhotra OP, Singh LR, Srivastava DK. Molecular asymmetry in alkaline phosphatase of Escherichia coli. Arch Biochem Biophys 1983; 220:519-29. [PMID: 6401985 DOI: 10.1016/0003-9861(83)90443-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Thermal inactivation of alkaline phosphatase of Escherichia coli has been studied at different temperatures (45 to 70 degrees C) and pHs (7.5, 9.0, and 10.0) for the commercial, buffer-dialyzed (pH 9.0) and EDTA-dialyzed (pH 9.0) enzymes. In each case, the inactivation exhibits biphasic kinetics consistent with the rate equation, (formula; see text) where A0 and A are activities at time zero and t, and k1 and k2 are first-order rate constants for the fast and slow phase, respectively. Values of k1 and k2 change independently with temperature, pH, and pretreatment (dialysis) of the enzyme. Time course of inactivation of the enzyme with excess EDTA and effect of Zn2+ ion concentration on the activity of EDTA-dialyzed enzyme have been investigated. The data suggest that the dimeric enzyme protein has two types of catalytic sites which have equal catalytic efficiency (or specific activity) but differ in several other properties. Structural implications of these results have been discussed.
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12
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Gettins P, Coleman JE. 31P nuclear magnetic resonance of phosphoenzyme intermediates of alkaline phosphatase. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)33271-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Del Arco A, Burguillo FJ, Roig MG, Usero JL, Izquierdo C, Herraez MA. Negative cooperativity in alkaline phosphatase from E. col: new kinetic evidence from a steady-state study. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1982; 14:127-40. [PMID: 7040134 DOI: 10.1016/0020-711x(82)90152-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
1. A study has been carried out on the steady-state kinetics followed by the alkaline phosphatase from Escherichia coli at different pH, temperatures, ionic strengths, phosphate concentrations and in the presence of the effectors such as Tris, NH4+--NH3 and CH3OH; p-nitrophenyl phosphate was used as substrate. 2. Contrary to what has generally been accepted, in most cases the enzyme follows non-Michaelian kinetics for a wide substrate concentration range, giving concave-down Lineweaver-Burk plots. Only at high phosphate concentrations (5 . 10(-3) M) and at high ionic strengths (2.0 M) is a linear Lineweaver-Burk plot obtained (Michaelian kinetics). 3. In order to analyse the kind of kinetics obtained, a non-linear regression fitting method was used to obtain rate vs substrate concentration equations as polynomial quotients of minimum degree with positive coefficients. 4. Most of the data obtained follows 2:2 degree type equations. 5. These results tend to suggest an idea of cooperativity rather than one of independence between the sites of the dimeric enzyme. A model is discussed for cooperativity between the sites with a wide concentration range giving concave-down Lineweaver-Burk plots.
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Roig MG, Burguillo FJ, Del Arco A, Usero JL, Izquierdo C, Herraez MA. Kinetic studies of the transphosphorylation reactions catalyzed by alkaline phosphatase from E. coli: hydrolysis of p-nitrophenyl phosphate and o-carboxyphenyl phosphate in presence of Tris. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1982; 14:655-66. [PMID: 7049787 DOI: 10.1016/0020-711x(82)90051-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
1. Transphosphorylation of p-nitrophenyl phosphate and o-carboxyphenyl phosphate to Tris, has been studied at alkaline and acid pH. 2. The rate of release for all reactions products was Tris-dependent for both substrates, with a slight maximum for phenol at alkaline pH. These dependences have been analyzed from a mechanistic standpoint. 3. Individual constants of rate of a simple transphosphorylation mechanism have been determined. 4. At high Tris concentration (greater than 1.0 M) a slight competitive inhibition has been observed. 5. Inhibition in NH4+-NH3Cl buffer has been found at alkaline pH but not at acid pH. It would therefore seem that the non-protonated NH2 group of Tris is responsible for inhibition. 6. The results suggest the formation of complexes between Tris and the enzyme. Other possible alternatives are also analyzed.
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Bloch W, Gorby MS. Catalytic mechanism of Escherichia coli alkaline phosphatase: resolution of three variants of the acyl-enzyme mechanism. Biochemistry 1980; 19:5008-18. [PMID: 7006682 DOI: 10.1021/bi00563a012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Three variants of the classical acyl-enzyme mechanism were compared theoretically with respect to the predicted transient kinetics of substrate hydrolysis by Escherichia coli alkaline phosphatase. In all three, acyl-enzyme hydrolysis was assumed to exist initially primarily as a noncovalent complex with the acid product, inorganic phosphate. In one mechanism, the pre-steady-state rate-controlling step was assumed to be the dissociation of acid product from its initial complex with enzyme. In the other two, pre-steady-state rate control was assigned to an enzyme isomerization occurring before or after substrate binding to free enzyme. Under concentration conditions of excess substrate and acid product, integrated rate laws were used to reject the possibility of pre-steady-state rate control by enzyme isomerization between phosphate dissociation and substrate binding. Whereas this mechanism predicts a pre-steady-state noncompetitive relationship between substrate and acid product, the stopped-flow kinetics of 4-methylumbelliferyl phosphate hydrolysis demonstrates a competitive relationship, consistent with either of the other two mechanisms. Under concentration conditions of stoichiometrically limiting substrate, computer simulations eliminated the possibility of rate control by enzyme isomerization after substrate binding. This mechanism predicts a substrate concentration dependence for the apparent first-order rate constant of substrate hydrolysis which disagrees with previously published data [Halford, S. E. (1971) Biochem. J. 125, 319--327]; the other two mechanisms are consistent with experiment. Comparison of transient kinetic theory and experiment under these two contrasting concentration conditions suggests strongly that the rate-controlling step in phosphate ester hydrolysis by E. coli alkaline phosphate is the dissociation of "sticky" acid product from its noncovalent complex with enzyme. This mechanism explains an anomaly in the stopped-flow kinetic trace, a substoichiometric pre-steady-state burst of alcohol product release.
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Abstract
We have measured the phosphorylation of the subunits of alkaline phosphatase in the steady state with several substrates and at several pH values. Our results vary from 80% phosphorylation of both subunits at pH7 to only 9% at pH 10. There is no evidence of anticooperativity. With the measurement of kcat, we are able to evaluate rate constants in a minimal scheme. The results show that the main rate influencing steps ar chemical dephosphorylation and dissociation of phosphate. The predominates at pH 7.0 but declines in importance as the pH is raised. Our rate constants for dissociation of phosphate are in agreement with recent NMR studies.
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Functional and structural properties of immobilized subunits of Escherichia coli alkaline phosphatase. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)85905-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Otvos J, Armitage I, Chlebowski J, Coleman J. 31P NMR of alkaline phosphatase. Dependence of phosphate binding stoichiometry on metal ion content. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(17)30069-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Hull WE, Halford SE, Gutfreund H, Sykes BD. 31P nuclear magnetic resonance study of alkaline phosphatase: the role of inorganic phosphate in limiting the enzyme turnover rate at alkaline pH. Biochemistry 1976; 15:1547-61. [PMID: 4092 DOI: 10.1021/bi00652a028] [Citation(s) in RCA: 119] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
31P nuclear magnetic resonance (NMR) was used to directly observe the binding of inorganic phosphate to alkaline phosphatase. Evidencq for the tight binding of 1.5-2.0 mol of inorganic phosphate per dimer of alkaline phosphatase is presented. Two distinct forms of bound phosphate are observed, one predominating above pH 7 and representing the non-covalent E-P1 complex and the other predominating below pH 5 and representing the covalent E-P1 complex. The 31P NMR line width of the E-P1 complex indicates that the dissociation of noncovalent phosphate is the rate-limiting step in the turnover of the enzyme at high pH.
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Chlebowski JF, Coleman JE. Mechanisms of Hydrolysis of O-Phosphorothioates and Inorganic Thiophosphate by Escherichia coli Alkaline Phosphatase. J Biol Chem 1974. [DOI: 10.1016/s0021-9258(19)42092-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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23
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Maguire RJ. Transient-phase kinetics of alpha-chymotrypsin and other enzyme systems. BIOCHIMICA ET BIOPHYSICA ACTA 1974; 341:1-14. [PMID: 4828844 DOI: 10.1016/0005-2744(74)90060-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Bloch W, Schlesinger MJ. Kinetics of Substrate Hydrolysis by Molecular Variants of Escherichia coli Alkaline Phosphatase. J Biol Chem 1974. [DOI: 10.1016/s0021-9258(19)42853-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Bloch W, Schlesinger MJ. The Phosphate Content of Escherichia coli Alkaline Phosphatase and Its Effect on Stopped Flow Kinetic Studies. J Biol Chem 1973. [DOI: 10.1016/s0021-9258(19)43574-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Halford SE, Lennette DA, Schlesinger MJ. A Mutationally Altered Alkaline Phosphatase from Escherichia coli. J Biol Chem 1972. [DOI: 10.1016/s0021-9258(19)45495-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Abstract
1. The hydrolysis of 2,4-dinitrophenyl phosphate by Escherichia coli alkaline phosphatase at pH5.5 was studied by the stopped-flow technique. The rate of production of 2,4-dinitrophenol was measured both in reactions with substrate in excess of enzyme and in single turnovers with excess of enzyme over substrate. It was found that the step that determined the rate of the transient phase of this reaction was an isomerization of the enzyme occurring before substrate binding. 2. No difference was observed between the reaction after mixing a pre-equilibrium mixture of alkaline phosphatase and inorganic phosphate, with 2,4-dinitrophenyl phosphate at pH5.5 in the stopped-flow apparatus, and the control reaction in which inorganic phosphate was pre-equilibrated with the substrate. Since dephosphorylation is the rate-limiting step of the complete turnover at pH5.5, this observation suggests that alkaline phosphatase can bind two different ligands simultaneously, one at each of the active sites on the dimeric enzyme, even though only one site is catalytically active at any given time. 3. Kinetic methods are outlined for the distinction between two pathways of substrate binding, which include an isomerization either of the free enzyme or of the enzyme-substrate complex.
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Lazdunski M, Petitclerc C, Chappelet D, Lazdunski C. Flip-flop mechanisms in enzymology. A model: the alkaline phosphatase of Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 1971; 20:124-39. [PMID: 4325354 DOI: 10.1111/j.1432-1033.1971.tb01370.x] [Citation(s) in RCA: 149] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Petitclerc C, Lazdunski C, Chappelet D, Moulin A, Lazdunski M. The functional properties of the Zn2(plus)-and Co2(plus)-alkaline phosphatases of Escherichia coli. Labelling of the active site with pyrophosphate, complex formation with arsenate, and reinvestigation of the role of the zinc atoms. EUROPEAN JOURNAL OF BIOCHEMISTRY 1970; 14:301-8. [PMID: 4319099 DOI: 10.1111/j.1432-1033.1970.tb00290.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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32
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Lazdunski C, Petitclerc C, Chappelet D, Lazdunski M. On the mechanism of the Zn2+ and Co2+-alkaline phosphatase of E. coli. Number of sites and anticooperativity. Biochem Biophys Res Commun 1969; 37:744-9. [PMID: 4900985 DOI: 10.1016/0006-291x(69)90954-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Halford SE, Bennett NG, Trentham DR, Gutfeund H. A substate-induced conformation change in the reaction of alkaline phosphatase from Escherichia coli. Biochem J 1969; 114:243-51. [PMID: 4897458 PMCID: PMC1184849 DOI: 10.1042/bj1140243] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
1. Benzyl phosphonates were prepared and their potentialities as chromophoric reagents for the exploration of the substrate-binding site of Escherichia coli alkaline phosphatase were investigated. 4-Nitrobenzylphosphonate is a competitive inhibitor of the enzyme. 2-Hydroxy-5-nitrobenzylphosphonate changes its spectrum on binding to the enzyme. This spectral change is reversed when the phosphonate is displaced from the enzyme by substrate. 2. The kinetics of the reaction of 2-hydroxy-5-nitrophenylphosphonate were studied by the stopped-flow and the temperature-jump techniques. It was found that the combination of the phosphonate with the enzyme occurred in two successive and reversible steps: enzyme-phosphonate complex-formation followed by rearrangement of the complex. The spectral change is associated with the rearrangement. At pH8 in 1m-sodium chloride at 22 degrees the rate constant is 167sec.(-1) for the rearrangement of the initially formed binary complex and is 18sec.(-1) for the reverse process. 3. It has previously been proposed that the reactions of phosphatase with its substrates include a distinct step between enzyme-substrate combination and chemical catalysis. The rate constant involved could be predicted but not measured from experiments with substrates. The value for the rate constant measured from the rate of the enzyme-phosphonate rearrangement is in excellent agreement with the predicted value. A model for the reaction mechanism is proposed that includes a conformation change in response to phosphate ester binding before phosphate transfer from substrate to enzyme.
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Levine D, Reid TW, Wilson IB. The free energy of hydrolysis of the phosphoryl-enzyme intermediate in alkaline phosphatase catalyzed reactions. Biochemistry 1969; 8:2374-80. [PMID: 4895019 DOI: 10.1021/bi00834a018] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Reynolds JA, Schlesinger MJ. Alterations in the structure and function of Escherichia coli alkaline phosphatase due to Zn2+ binding. Biochemistry 1969; 8:588-93. [PMID: 4893577 DOI: 10.1021/bi00830a019] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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39
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Fernley HN, Walker PG. Studies on alkaline phosphatase. Transient-state and steady-state kinetics of Escherichia coli alkaline phosphatase. Biochem J 1969; 111:187-94. [PMID: 4884484 PMCID: PMC1187806 DOI: 10.1042/bj1110187] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
1. The transient-state and steady-state phases of the reaction between Escherichia coli alkaline phosphatase and 4-methylumbelliferyl phosphate were investigated by using a fluorimetric stopped-flow technique. 2. At low substrate concentration (5mum) in the pH range 3.8-6.3 there was an initial rapid liberation of up to 1mole of 4-methylumbelliferone/mole of enzyme. 3. At very low substrate concentration (0.1mum) in the pH range 4.9-5.9 an initial lag in 4-methylumbelliferone production was observed, from which values for k(+1) and k(-1) could be obtained. 4. The pH profiles for the rates of phosphorylation and dephosphorylation are quite different, and it is postulated that an ionizing group which determines the conformation during the phosphorylation step is not involved in the dephosphorylation step. 5. The binding constants for substrate and P(i) are similar throughout the pH range 4-8. The ionization of substrate or P(i) appeared to have no marked effect on the binding.
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