D-lactate is present in much larger amount than L-lactate in cephalopods and gastropods

Abstract

It has long been known that only L-lactic acid is found in animals and that D-lactic acid is produced in microbial organisms. During the course of study of D-lactate formation from methylglyoxal (the methylglyoxal bypass) in animals, we found that D-form is mainly present in Octopus vulgaris and very little L-lactate was found in octopus muscle. There is an inverse relationship between octopus and normal animals for concentrations of D- and L-lactate. The activities of D-lactate dehydrogenase (D-LDH) was predominantly found in octopus muscle, while L-LDH activity was scarcely detected. Methylglyoxal was the best substrate for D-lactate formation in octopus foot homogenate and pyruvate was the second best substrate. It was also found that D-lactate is present in much higher amounts than the L-form in some animals or plants.