MULTIPLE EFFECTS OF PROTEIN-X ACETYLATION ON THE REGULATION OF PYRUVATE-DEHYDROGENASE COMPLEX ACTIVITY - A MATHEMATICAL-MODEL

A kinetic model of pyruvate dehydrogenase complex is proposed, which t akes into account the known data on the structural and functional rela tionships between the second component (dihydrolipoyl transacetylase [ EC 2.3.1.12]), protein X, and the third component (dihydrolipoyl dehyd rogenase [EC 1.6.4.3]) in electron transfer. In addition to the previo usly revealed role of protein X acetylation in switching the complex t o a lower activity mode, a promoting effect of the acetylated lipoyl m oiety of protein X on the tightly bound protein kinase, capable of ina ctivating the first catalytic component (pyruvate decarboxylase [EC 1. 2.4.1]), is considered. It is shown that the two regulatory effects of protein X acetylation together can shift the complex to a self-sustai ned oscillating mode.