Differences in some properties of lactate dehydrogenase from muscles of the carp Cyprinus carpio and trout Salmo gairdneri

Abstract

Some catalytic and kinetic properties of lactate dehydrogenase (LDH) isolated from trout and carp skeletal muscles were compared. The specific activity of LDH in the carp muscle was lower by about one third than the activity in the trout muscle. Temperature and pH optima for LDH isolated from the carp muscle were higher than those for the trout muscle LDH. Moreover, in direct reaction, the carp muscle LDH had a higher affinity both for pyruvate and for NADH, i.e., it had lower KM values. Instead, the trout muscle LDH showed the positive kinetic cooperativity (the Hill coefficient > 1) of the substrate and coenzyme binding sites. Thus, the carp LDH seems to function more effectively under anaerobic conditions and at higher temperatures.