Active-site modification of mammalian pyruvate dehydrogenase by pyridoxal 5'-phosphate.
Active-site modification of mammalian pyruvate dehydrogenase by pyridoxal 5'-phosphate.
复制标题
5-磷酸吡哆醛对哺乳动物丙酮酸脱氢酶的活性位点进行修饰。
DOI：
10.1021/bi00346a026
复制
发表时间：
1985
期刊：
影响因子：
2.9
通讯作者：
Reed,LJ
中科院分区：
文献类型：
--
作者：
Stepp,LR;Reed,LJ
The pyruvate dehydrogenase multienzyme complex from bovine kidney and heart is inactivated by treatment with pyridoxal 5'-phosphate and sodium cyanide or sodium borohydride. The site of this inhibition is the pyruvate dehydrogenase (Et) component of the complex. Inactivation of E, by the pyridoxal phosphate-cyanide treatment was prevented by thiamin pyrophosphate. Equilibrium binding studies showed that Ej containstwo thiamin pyrophosphate binding sites per molecule {2ß2) and that modification of Et increased the dissociation constant (Rd) for thiamin pyrophosphate about 50-fold. Incorporation of ap-proximately 2.4 equiv of 14CN per mole of Ej tetramer in the presence of pyridoxal phosphate resulted in about a 90% loss of E, activity. Radioactivity was incorporated predominately into the E¡ a subunit. Radioactive A^-pyridoxyllysine was identified in an acid hydrolysate of the,-pyridoxal phosphate complex that had been reduced with NaB3H4. The data are interpreted to indicate that in the presence of sodium cyanide or sodium borohydride, pyridoxal phosphate reacts with a lysine residue at or near the thiamin pyrophosphate binding site of EvThis binding site is apparently located on the a subunit.
