[Phosphorylation of lactate dehydrogenase by purified plasma membranes of loach liver cells: stimulation with insulin].

It is established that insulin enhances the ability of the loach liver plasma membranes to phosphorylate lactate dehydrogenase. In the case of insulin-treated plasma membranes the amount of incorporated 32P is more than 4 times higher than that of the basal level. It is concluded that insulin-stimulated plasma membrane-dependent phosphorylation of the enzyme is one of the possible molecular mechanisms of hormone action on intracellular metabolism.

[Protein fractions of the ova, embryos and skeletal muscles of the loach affecting the stability and activity of lactate dehydrogenase].

When lactate dehydrogenase obtained from Misgurnus muscles and purified to the homogeneous state is incubated for 16 hat 38 degrees C, its activity lowers down to 10% of the initial value. Extracts of egg cells, embryos or skeletal muscles of the mentioned fish species added to the enzyme solution decrease considerably its inactivation. Proteins stabilizing the activity of lactate dehydrogenase are revealed in the supernatant liquid obtained after salting out of the above extracts with 60% sulphate ammonium saturation.

[Insulin and 17-oxycorticosteroids in unfertilized eggs and in embryos of the loach].

Loach eggs are stated to possess some quantities of insulin or insulin-like substances with a positive reaction to antiinsulin antiserum. The level of these components is five times as high 30 minutes after fertilization, and does not change for the next 20 hours of the embryo development. No 17-oxycorticosteroids were detected in loach eggs and embryos during first four hours of the development; they appeared only at the blastula stage and at the state of gastrula their level increases considerably.

[Effect of extracts from loach eggs and embryos exposed to insulin on glucose-6-phosphate dehydrogenase activity].

It is established that the incubation of glucose-6-phosphate dehydrogenase solution (33 micrograms of enzymic protein per 1 ml) with extracts of unfertilized loach eggs and embryos results in a marked stabilization of the enzyme with respect to its inactivation. Extracts from the embryos preliminary affected by insulin possessed a lower stabilizing ability, the hormonal effect being removed to a considerable extent by actinomycin D and cycloheximide.

[Influence of loach egg- and embryo-extract on the activity of lactate dehydrogenase in the presence of insulin].

Studies of the pig muscle lactate dehydrogenase (LDH) activity were permormed after incubating the enzyme solution with extracts of loach (Misgurnus fossilis) eggs and embryos, which were subjected to the influence of insulin hydrocortisone as well as to insulin combination with actinomycin D, cycloheximide or puromycin. The insulin alone is established to decrease the inactivating ability of the investigated extracts on the lactate dehydrogenase activity, when antibiotics removed to a considerable extent the influence of hormone. In the eggs and embryos there are proteins activating and stabilizing the LDH molecule.