Genetic basis of opine dehydrogenase activities in the Pacific oyster, Crassostrea gigas

Tw polymorphic gene loci coding for enzyme proteins responsible for multipl e opine dehydrogenase activities are expressed in the adductor muscle of th e Pacific oyster, Crassostrea gigas. One locus, Strdh(Alpdh-1), codes for a n isozyme that demonstrates highest catalytic activity with glycine, but is also capable of using alpha-L-alanine, L-serine and beta-alanine as substr ates. The second locus, Alpdh-2, codes for an isozyme specific to alpha-L-a lanine. Electrophoretic gels stained using alpha-L-alanine as substrate rev eal presence of both isozymes in adductor muscle tissues. The STRDH(ALPDH-1 ) isozyme alone is detected in adductor muscle, with glycine as substrate, whereas only ALPDH-2 is detected in hepatopanereas, mantle and gill tissues with alpha-L-alanine. Only two enzyme proteins are responsible for multipl e opine dehydrogenase activities in the adductor muscle of the oyster. The value of gene-enzyme specific allozyme patterns for identification of, and discrimination between, enzyme proteins possessing broad substrate specific ity is briefly discussed. (C) 1998 Published by Elsevier Science Inc. All r ights reserved.