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Title: Regulatory site of inorganic pyrophosphatase. Nonhyperbolic kinetics of enzymatic reaction at low substrate concentrations

Abstract

The initial rate of PP/sub 1/ hydrolysis by inorganic pyrophosphatase from baker's yeast was analyzed as a function of the concentrations of the Mg-PP/sub 1/ complex (substrate) and Mg/sup 2 +/ ions (activator) at substrate concentrations down to 0.1 ..mu..M. Lineweaver-Burk plots for the enzyme in equilibrium with Mg/sup 2 +/ ions were nonlinear at fixed Mg/sup 2 +/ concentrations, which cannot be explained within the framework of previously proposed models of the reaction. The nonlinearity is retained for the monomeric form of the enzyme and indicates that the enzyme has a regulatory site capable of tightly binding free PP/sub 1/ (K/sub d/ approx. 0.02 ..mu..M). A new model of the reaction is proposed in which Mg-PP/sub 1/, PP/sub 1/, and Mg/sup 2 +/ are bound to the enzyme in random order and filling of the regulatory site decreases the dissociation constant of the protein-Mg complex from 4.7 to 0.025 mM. It was concluded that PP/sub 1/ and Mg/sup 2 +/ are regulators of pyrophosphatase activity under physiological conditions.

Authors:
; ;
Publication Date:
Research Org.:
Lomonosov Moscow State Univ., Moscow (Russian Federation)
OSTI Identifier:
5841969
Resource Type:
Journal Article
Journal Name:
Biochemistry (Engl. Transl.); (United States)
Additional Journal Information:
Journal Volume: 51:2; Other Information: Translated from Biokhimiya; 51: No. 2, 179-187(Feb 1986)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; PHOSPHATASES; ENZYME ACTIVITY; PYROPHOSPHATES; BIOCHEMICAL REACTION KINETICS; ENZYMATIC HYDROLYSIS; RADIOENZYMATIC ASSAY; BIOCHEMISTRY; COMPUTERIZED SIMULATION; DISSOCIATION; LABELLED COMPOUNDS; LABELLING; MAGNESIUM COMPLEXES; MAGNESIUM COMPOUNDS; MATHEMATICAL MODELS; NONLINEAR PROBLEMS; PHOSPHORUS 32; QUANTITY RATIO; SUBSTRATES; YEASTS; ALKALINE EARTH METAL COMPLEXES; ALKALINE EARTH METAL COMPOUNDS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; CHEMICAL REACTIONS; CHEMISTRY; COMPLEXES; DAYS LIVING RADIOISOTOPES; DECOMPOSITION; ENZYMES; ESTERASES; FUNGI; HYDROLASES; HYDROLYSIS; ISOTOPES; KINETICS; LIGHT NUCLEI; LYSIS; MICROORGANISMS; NUCLEI; ODD-ODD NUCLEI; OXYGEN COMPOUNDS; PHOSPHORUS COMPOUNDS; PHOSPHORUS ISOTOPES; PLANTS; RADIOISOTOPES; REACTION KINETICS; SIMULATION; SOLVOLYSIS; 550201* - Biochemistry- Tracer Techniques

Citation Formats

Pavlov, A R, Baikov, A A, and Avaeva, S M. Regulatory site of inorganic pyrophosphatase. Nonhyperbolic kinetics of enzymatic reaction at low substrate concentrations. United States: N. p., 1986. Web.
Pavlov, A R, Baikov, A A, & Avaeva, S M. Regulatory site of inorganic pyrophosphatase. Nonhyperbolic kinetics of enzymatic reaction at low substrate concentrations. United States.
Pavlov, A R, Baikov, A A, and Avaeva, S M. 1986. "Regulatory site of inorganic pyrophosphatase. Nonhyperbolic kinetics of enzymatic reaction at low substrate concentrations". United States.
@article{osti_5841969,
title = {Regulatory site of inorganic pyrophosphatase. Nonhyperbolic kinetics of enzymatic reaction at low substrate concentrations},
author = {Pavlov, A R and Baikov, A A and Avaeva, S M},
abstractNote = {The initial rate of PP/sub 1/ hydrolysis by inorganic pyrophosphatase from baker's yeast was analyzed as a function of the concentrations of the Mg-PP/sub 1/ complex (substrate) and Mg/sup 2 +/ ions (activator) at substrate concentrations down to 0.1 ..mu..M. Lineweaver-Burk plots for the enzyme in equilibrium with Mg/sup 2 +/ ions were nonlinear at fixed Mg/sup 2 +/ concentrations, which cannot be explained within the framework of previously proposed models of the reaction. The nonlinearity is retained for the monomeric form of the enzyme and indicates that the enzyme has a regulatory site capable of tightly binding free PP/sub 1/ (K/sub d/ approx. 0.02 ..mu..M). A new model of the reaction is proposed in which Mg-PP/sub 1/, PP/sub 1/, and Mg/sup 2 +/ are bound to the enzyme in random order and filling of the regulatory site decreases the dissociation constant of the protein-Mg complex from 4.7 to 0.025 mM. It was concluded that PP/sub 1/ and Mg/sup 2 +/ are regulators of pyrophosphatase activity under physiological conditions.},
doi = {},
url = {https://www.osti.gov/biblio/5841969}, journal = {Biochemistry (Engl. Transl.); (United States)},
number = ,
volume = 51:2,
place = {United States},
year = {Sun Aug 10 00:00:00 EDT 1986},
month = {Sun Aug 10 00:00:00 EDT 1986}
}