[Inactivation of yeast apopyruvate decarboxylase by lipophilic n-alkyl-substituted thiazole salts].
Yeast apopyruvate decarboxylase is irreversibly inactivated by 3-dodecyl-4-methylthiazolium bromide (I), 3-dodecyl-4-methyl-5-beta-hydroxyethylthiazolium bromide (II), 3-hexadecyl-4-methyltiazolium bromide (III), 3-hexadecyl-4-methyl-5-beta-hydroxyethyliazolium bromide (IV). 3-Octyl-4-methylthiazolium bromide (V) possesses insignificant inactivating properties. The relationship between residual enzymatic activity and concentration of thiazolium salts (II, IV) which are more similar structural analogs of thiamine is of the S-like pattern. In the case of thiazolium salts (I, III) this relationship is almost linear. The measure of inactivation of apopyruvate decarboxylase in the presence of substances (I-IV) increases with the hydrocarbon chain length of n-alkyl substituent of the quaternary nitrogen atom of the thiazolium salt. The calculated second-order-rate constants are 5.43.10(2) (I) 1.52.10(3) (II). 2.83.10(4) (III). 4.85.10(4) M-1 min-1 (IV). The UV spectroscopic method has shown that a hypsochromic shift of longwave absorbtion maxima and a decrease of their extinction occur under interaction of thiazolium salts (I-V) with tryptophan. This fact evidence for possible complexing of compounds (I-V) with indole residues of protein. The hydrophobic interactions are supposed to be a crucial factor in the inactivation mechanism of yeast apopyruvate decarboxylase.
Vovk
A I
AI
Krishko
S S
SS
D007527:Isoenzymes / Q000037:antagonists & inhibitors*; D007700:Kinetics; D011767:Pyruvate Decarboxylase / Q000037:antagonists & inhibitors*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology*; D012492:Salts; D013056:Spectrophotometry, Ultraviolet; D013844:Thiazoles / Q000494:pharmacology*
D007527:Isoenzymes; D012492:Salts; D013844:Thiazoles; D011767:Pyruvate Decarboxylase
Inaktivatsiia drozhzhevoĭ apopiruvatdekarboksilazy lipofil'nymi n-alkilzameshchennymi soliami tiazoliia.