[Immunochemical study of lactate dehydrogenase polymorphism in the loach Misgurnus fossilis]

Data from experiments on antiserum against B4-isoenzyme of lactate dehydrogenase confirmed the previously made assumption that the main isoenzyme of lactate dehydrogenase of most differentiated tissues of the loach Misgurnus fossilis, which is inhibited by AgNO3, is made up by A-subunits, while that of the isoenzymes whose activity is predominant in the ovaries and embryos of this teleost species and which are normally resistant to AgNO3, are made up by B-subunits. The C4-isoenzyme of lactate dehydrogenase which is liver-specific is highly sensitive to inactivation by anti-B4 antiserum. The "minor" isoforms of the enzyme detected in the enzymatic spectrum of the ovaries, embryos and larvae, which are inhibited by AgNO3, are subjected to inactivation by anti-B4- and are insensitive to anti-A4 antiserum against A4-isoenzyme of lactate dehydrogenase from loach skeletal muscles. These data and a gradual disappearance of the isoforms simultaneously with a decrease of yolk in developing larvae suggest that they appeared due to post-translational modifications of the B-subunits, predominant in lactate dehydrogenase of ovaries and embryos by certain components of the yolk.