Acceptor substrate inhibits transketolase competitively with respect to donor substrate

Two substrates of the transketolase reaction are known to bind with the enzyme according to a ping-pong mechanism [1]. It is shown in this work that high concentrations of ribose-5-phosphate (acceptor substrate) compete with xylulose-5-phosphate (donor substrate), suppressing the transketolase activ...

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Published inBiochemistry (Moscow) Vol. 65; no. 10; pp. 1202 - 1205
Main Authors Solov'eva, O N, Meshalkina, L E, Kovina, M V, Selivanov, V A, Bykova, I A, Kochetov, G A
Format Journal Article
LanguageEnglish
Published United States 01.10.2000
Subjects
Catalytic Domain
Circular Dichroism
Enzyme Inhibitors - pharmacology
Kinetics
Pentosephosphates - metabolism
Ribosemonophosphates - metabolism
Ribosemonophosphates - pharmacology
Substrate Specificity
Transketolase - antagonists & inhibitors
Transketolase - chemistry
Transketolase - metabolism
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Summary:Two substrates of the transketolase reaction are known to bind with the enzyme according to a ping-pong mechanism [1]. It is shown in this work that high concentrations of ribose-5-phosphate (acceptor substrate) compete with xylulose-5-phosphate (donor substrate), suppressing the transketolase activity (Ki = 3.8 mM). However, interacting with the donor-substrate binding site on the protein molecule, the acceptor substrate, unlike the donor substrate, does not cause any change in the active site of the enzyme. The data are interesting in terms of studying the regulatory mechanism of the transketolase activity and the structure of the enzyme-substrate complex.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:0006-2979