The identification, function and cold adaptation of the proteins/enzymes in Antarctic fish from amount and distribution of lactate dehydrogenase from seven different tissues

The likely function of lactate dehydrogenase (LDH), the only isozyme found in these fish, was examined by looking at the amount and distribution of LDH in a variety of both temperate and Antarctic fish. Small samples were collected from 7 different tissues (eye, brain, heart, liver, spleen and red and white muscles) of 4-8 individuals of each species of fish (Pagothenia borchgrevinki, Trematomus nicolai, T. newnesi and T. pennelli).

Each sample was assayed by creating an extract from a tissue chunk, removing the debris by centrifugation and the produced supernatant assayed for enzyme activity spectrophotometrically. To determine the nature of the new isozyme found in these fish, tissue was collected and stored. A protocol was developed to stabilize the isozyme, to be able to purify it and then determine the amino acid sequence of the amino terminus, in order to identify the new type of isozyme.