L(+)-lactate dehydrogenase of Clostridium acetobutylicum is activated by fructose-1,6-bisphosphate

Abstract

Cells of Clostridium acetobutylicum contained an NADH-dependent L(+)-lactate dehydrogenase which was activated specifically by fructose-1,6-bisphosphate (F-1,6-P2), with calcium or magnesium ions as positive effectors. During the purification steps the enzyme was very unstable. The purified enzyme existed in a tetrameric structure (apparent Mr of about 159 kDa) and had its pH optimum at pH 5.8. Little activity was left at pH values below 5.0. The enzyme was unidirectional, catalysing only the reduction of pyruvate. The half maximal activation of the reaction velocity with F-1,6-P2 depended on the pyruvate concentration. © 1987.