[Inhibition of yeast pyruvate decarboxylase by alkyl phosphates].
It is found that yeast pyruvate decarboxylase is inhibited by alkyl phosphates. Inhibition is competitive with respect to a substrate. The inhibition constants with n-butyl and n-heptyl esters of phosphoric acid are the values of the same order of magnitude. With an increase in the length of the alkyl phosphates hydrocarbon chain from 7 to 10 carbon atoms inhibition constants change drastically. For n-heptyl phosphate and n-decyl phosphate values KI are equal to 1.6 x 10(-4) M and 1.7 x 10(-6) M, respectively. A further increase in the number of carbon atoms in the alkyl substituent of phosphoric acid ester induces no reduction of the inhibition constant. Multiple-inhibitor experiments of pyruvate decarboxylase show that inorganic phosphate and n-decyl ester of phosphoric acid are mutually exclusive. It is suggested that the inhibition mechanism with alkyl phosphates includes the competition of the phosphoric acid residue with alpha-ketocarboxyl group of pyruvate as well as the interaction between a hydrocarbon radical and hydrophobic parts on the enzyme surface, one of them being outside the substrate binding site.
Vovk
A I
AI
Lazukina
L A
LA
Murav'eva
I V
IV
Kukhar'
V P
VP
D000478:Alkylation; D001667:Binding, Competitive / Q000502:physiology; D010710:Phosphates / Q000494:pharmacology*; D011767:Pyruvate Decarboxylase / Q000037:antagonists & inhibitors*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013379:Substrate Specificity
D010710:Phosphates; D011767:Pyruvate Decarboxylase
Ingibirovanie drozhzhevoĭ piruvatdekarboksilazy alkilfosfatami.