Lactate dehydrogenase isoenzyme patterns in bird, carp and mammalian sera

Isoenzyme patterns of lactate dehydrogenase (EC 1.1.1.27) in avian sera are described and compared with those of carp and some mammals. The predominant portion of lactate dehydrogenase in avian sera was concentrated in the muscular form of the enzyme (lactate dehydrogenase 5). Most mammalian sera (with the exception of rat serum) showed a different pattern, in which the main portion of lactate dehydrogenase activity migrated in the first three anodic fractions. Fish serum lactate dehydrogenase isoenzymes were distributed similarly to those of mammals. The electrophoretic mobility of bird lactate dehydrogenase isoenzymes in a pH gradient of 3 to 9 was different from that of carp, cattle and rabbit. Bird lactate dehydrogenase isoenzymes were localized in the pH region of 5.8 to 8.1. In contrast, the mammalian isoenzymes were more acidic, with pI values in the range of 4.5 to 7.3. Lactate dehydrogenase isoenzymes of carp migrated in a narrow pH range of 5.2 to 6.5.