Partial Purification and Some Properties of ATP: Citrate Lyase from the Oleaginous Yeast Lipomyces starkeyi

Abstract

ATP:citrate lyase has been purified some 20-fold from the oleaginous yeast, Lipomyces starkeyi CBS 1809. The enzyme, which is labile, was stabilized by the addition of ATP and citrate to extraction buffers. Michaelis-Menten kinetics were exhibited towards ATP and citrate. The molecular weight of the enzyme was determined to be approximately 510000. There was a specific requirement for ATP for activity. No activity was observed in the absence of Mg2+, although Co2+ and Mn2+ could partially substitute for Mg2+. ADP inhibited activity (50% inhibition at 1 mM), as did long-chain fatty acyl-CoA esters (50% inhibition with 4m oleoyl-CoA). The possibility of control of ATP:citrate lyase activity by fluctuations in the prevailing energy charge or by changes in the intracellular concentrations of long-chain fatty acyl-CoA esters is discussed.