[The rate of gluconeogenesis and the activity of its key enzymes in the kidneys of the developing chick embryo].

The rate of glucose formation from lactate was studied in tubules isolated from the kidneys of chick embryos of different age and for one- and two-day-old chickens. Changes in the activity of the key enzymes of gluconeogenesis have also been followed in the chick embryo kidneys. The rate of gluconeogenesis markedly increased after hatching.

[The isoenzyme composition of liver pyruvate kinase from hens in ontogeny].

Only one isozyme M2 of pyruvate kinase was found in the liver of hens at all stages of embryonic and postembryonic development. No analogue to isozyme L from the liver of mammals was found. During embryogenesis and postnatal life, isozyme M2 is presented by two forms which differ in pI values.

[The enzymes of fructose metabolism in the liver of chick embryos].

The activity of fructose cycle enzymes remains practically constant in chick embryonic liver during ontogenesis. Change in ratio of aldolase A to B activities was detected. It is suggested that fructose enters the cycle via the sorbitol pathway in which aldose reductase and sorbitol dehydrogenase are involved.

[The key enzymes of the alternative pathways of serine utilization in gluconeogenesis in chickens during individual development].

It has been shown that in embryonic liver and kidney of chicks, serine is involved into gluconeogenesis almost exclusively via serine-pyruvate aminotransferase. This relationship stands true also for the liver of adult hens. On the contrary, in the kidney of adult hens, there is a significant increase in the activity of serine dehydratase, as compared to the level of the activity of this enzyme in embryogenesis and in the liver of adult hens.

[Supramolecular organization of glycolytic enzymes].

On the basis of the analysis of the data on adsorption of glycolytic enzymes to structural proteins of skeletal muscle and to erythrocyte membranes, the data on enzyme-enzyme interactions and the data on the regulation of activity of glycolytic enzymes by cellular metabolites the structure of glycolytic enzyme complex adsorbed to a biological support has been proposed. The key role in the formation of the multienzyme complex belongs to 6-phosphofructokinase. The enzyme molecule has two association sites, one of which provides the fixation of 6-phosphofructokinase on the support and another is saturated by fructose-1,6-bisphosphate aldolase.