[The rate of gluconeogenesis and the activity of its key enzymes in the kidneys of the developing chick embryo]. / Skorost' gliukoneogeneza i aktivnost' ego kliuchevykh fermentov v pochkakh razvivaiushchegosia zarodysha kuritsy.

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. Changes in the rate of gluconeogenesis during embryogenesis are correlated with those in the activity of key enzymes of this process: phospho(enol) pyruvate carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase. Glucose-6-phosphatase was shown to be polyfunctional in the kidneys of chick embryos and chickens: in addition to hydrolysis of glucose-6-phosphate with formation of glucose, the enzyme is capable of phosphorylating glucose with the help of phosphate donors, carbamyl-phosphate and pyrophosphate.

[The isoenzyme composition of liver pyruvate kinase from hens in ontogeny]. / K voprosu ob izozimnom sostave piruvatkinazy pecheni kur v ontogeneze.

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. Throughout embryonic and postembryonic development, pyruvate kinase is presented by two forms which differ in their substrate affinity.

[The enzymes of fructose metabolism in the liver of chick embryos]. / Fermenty obmena fruktozy v pecheni zarodyshei kur.

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]. / Kliuchevye fermenty al'ternativnykh putei ispol'zovaniia serina v gliukoneogeneze u kur v khode individual'nogo razvitiia.

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]. / Nadmolekuliarnaia organizatsiia fermentov glikoliza.

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. The multienzyme complex fixed on structural proteins of skeletal muscle contains one tetrameric molecule of 6-phosphofructokinase and at two molecules of other glycolytic enzymes. Hexokinase is not involved in the complex composition. The molecular mass of the multienzyme complex is about 2,6 X 10(6) Da. The formation of the multienzyme complex leads to the compartmentation of the glycolytic process. The problem of integration of physico-chemical mechanisms of enzyme activity regulation (allosteric, dissociative and adsorptive mechanisms) is discussed.

Supramolecular organization of glycolytic enzymes.

On the basis of the analysis of the data on adsorption of glycolytic enzymes to structural proteins of skeletal muscles and to the 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 the glycolytic enzymes complex adsorbed to a biological support has been proposed. The key role in the formation of 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. The multienzyme complex contains one tetrameric molecule of 6-phosphofructokinase and two molecules of each of other glycolytic enzymes. Hexokinase is not a part of the complex. The molecular mass of the multienzyme complex is about 2.6 X 10(6) daltons. The multienzyme complex has symmetry axis of second order. The formation of the multienzyme complex leads to the compartmentation of glycolytic process. The problem of integration of physico-chemical mechanisms of enzyme activity regulation (allosteric, dissociative and adsorptive mechanisms) is discussed.

[Pyruvate dehydrogenase activation in the skeletal muscles of the chick embryo during electrostimulation]. / Aktivatsiia piruvatdegidrogenazy v skeletnykh myshtsakh kurinogo zarodysheva pri élektrostimuliatsii.

The pyruvate dehydrogenase activity in the skeletal muscle during chicken embryo-genesis and early postnatal life amounts to 550 +/- 50 mU per g tissue, on the average; electrostimulation (1 Hz) induced a two-fold increase in its activity starting from the 15th day of incubation.

[Activation of glycogenolysis during electrostimulation of the skeletal muscles in the chick embryo under aerobic conditions]. / Aktivatsiia glikogenoliza pri élektrostimuliatsii skeletnykh myshts kruinogo zarodysha v aérobnykh usloviiakh.

A cooperative activation of glycogenolysis was found in the chick embryo skeletal muscles (upon electrostimulation) on the 13th day of incubation (stage 39 after Hamburger, Hamilton, 1951).

[Glycogen phosphorylase isozymes from chicken tissues and changes in the isozyme ratio during ontogenesis]. / Izozimy glikogenfosforilazy tkanei kuritsy i izmeneniia sootnocheniia izozimov v ontogeneze.

The isolation of isozymes Ib, IIIb and Lb of glycogen phosphorylase (EC 2.4.1.1) from chicken tissue is described. Isozymes Ib and IIIb have the same value of Km(G-1-P), i.e. 6.2 mM at 2 mM AMP but differ in A0.5(AMP). Isozyme Lb is characterized by S0.5(G-1-P) of 15 mM at 2 mM AMP and A0.5(AMP) of 600 muM at 20 mM G-1-P; for isozyme La these parameters are 3.7 mM and 20 muM, respectively. All the three isozymes reveal distinct immunochemical differences. In embryonic skeletal muscle the enzyme is represented by isozymes L and III up to the 15th way of embryogenesis; after the 17th day--only by isozyme III. In chicken liver the enzyme is represented only by isozyme L beginning with the 9th day of embryogenesis. At the beginning of tissue differentiation stage (4th day of embryogenesis) fetal tissues were found to contain isozymes L and IL.

[Changes in the glycogen phosphorylase isoenzyme spectrum in the rat liver and skeletal muscles in ontogeny]. / Izmeneniia izofermentnogo spektra glikogen fosforilazy v pecheni i skeletnykh myshtsakh krysy v ontogeneze.

Changes in the isozyme patterns of glycogen phosphorylase in the rat liver and skeletal muscles were studied during ontogenesis. The presence of a minor component both in the muscles and the liver during embryogenesis was shown by means of immunochemical titration and disc-electrophoresis. The possible nature of this component, its identity with the "embryonic" phosphorylase isozyme [1] and the hybrid form of IL enzyme [2,3].

[Glycogen metabolic enzymes in the skeletal muscles of the developing chick embryo]. / Fermenty obmena glikogena v skeletnykh myshtsakh razvivaiushchegosia zarodysha kuritsy.

In the skeletal muscles of the chick embryo from the 10th till the 15th day of embryogenesis, phosphorylase (EC. 2.4.1.1) is represented by two isozymes one of which corresponds, by electrophoretic mobility, to the liver phosphorylase and another to phosphorylase of the skeletal muscles of the adult rat. From the 17th day of embryogenesis on only one isozyme of phosphorylase is found in the skeletal muscles which is identical with that of the skeletal muscles of the adult bird. The isozyme spectrum of phosphorylase of the whole 4 days old embryo contains, besides phosphorylase L, a special "embryonic" isozyme which differs from that of the skeletal muscles by immunochemical characteristics and electrophoretic mobility. From the 10th day of embryogenesis till hatching, the activity of phosphorylase of the skeletal muscles increases more than 50 times and that of glycogen synthetase (EC. 2.4.1.11) only 4 times.

[Changes in the glycogen synthetase isoenzyme makeup and the formation of glycogen organelles in the liver of the developing rat embryo]. / Izmeneniia izofermentnogo sostava glikogen sintetazy i formirovanie glikogenovoi organelly v pecheni razvivaiushchegosia zarodysha krysy.

Glycogen synthetase of the rat embryo liver is represented until the 14th day of embryogenesis by the enzyme of "embryonic" (or so called muscle) type. This type is gradually replaced for an isozyme (isozymes) characteristic of the rat adult liver from the 15th till the 18th days of embryogenesis. The formation of glycogen organelles (glucosomes) in the embryonic liver occurs during the 18--19th day of development, i. e. after the full replacement of "embryonic" glycogen synthetase.

[Glycogen phosphorylase isoenzymatic makeup changes in the liver of birds and mammals in ontogeny]. / Izmeneniia izofermentnogo sostava glikogen fosforilazy v pecheni ptits i mlekopitaiushchikh v ontogeneze.

It was established by means of immunochemical titration that phosphorylase of the chickliver, beginning from the 8th day of embryogenesis, was represented by an isozyme, immunochemically identical or closely related to mammalian phosphorylase L. At the early stage of development (4th day) the chick embryo contained both isozyme L (ca. 60%) and isozyme, closely related to mammalian isozyme I. In the liver of 15 days old rat embryos the ratio of isozymes I and L equaled 1 : 2. It is suggested that the ratio of L and IL is close to 1 : 1. The isozyme IL is replaced for the isozyme L completely during the second ten day period of postnatal development.

[Independence of the (NAD+):(NADH) ratio from the adenylic system in the liver cytoplasm of the developing chick embryo]. / Nezavisimost' otnosheniia (NAD+):(NADH) ot adenilovoi sistemy v tsitoplazme pecheni razvivaiushchegosia zarodysha kuritsy.

No dependence was found between the index of the adenylic system phosphorylated state (ATP) : (ADP) (HPO2-4), the ratios (ATP) : (ADP) and (ATP : (ADP + AMP), on one hand, and the ratio (NAD+) : (NADH) in the cytoplasm, on the other one. The maximum value of the ratio (ATP) : (ADP) (HPO2-4) was observed on the 17th day of development and correlated with the maximum rate of gluconeogenesis. The ratio (NAD+) : (NADH) in the cytoplasm suffered no changes until hatching and decreased twice thereafter.

[Enzymes of glycogen metabolism in chick embryo liver]. / Fermenty obmena glikogena v pecheni embriona tsyplenka.

At all stages of ontogenesis glycogen phosphorylase (EC 2.4.1.1) from liver chick embryos in represented by an isoenzyme whose properties are close to those of isoenzyme IL or F. Total enzyme activity (a+b forms) from the 8th day of development up to hatching gradually increases 1.5-fold, a practically complete activation of enzyme being observed by the end of embryogenesis. Phosphorylase b possesses high catalytic activity in the presence of 1 mM AMP and it activated by protamine and 0.2 M Na2SO4. Glycogen synthetase (EC 2.4.1.11) has a constant Km(UDFG) value during ontogenesis. This value is about 5.10(-4) M in the presence of 10 mM glucose-6-phosphate, both for I- and D-forms of enzyme. The total enzyme activity reaches its maximum on the 17th postembryonic day and is decreased more than 6-fold thereafter. In the course of embryogenesis the I/D ratio is increased from 0.2 on the 8th day of development up to 0,45 during extensive accumulation of glycogen and falls down to 0.33 before hatching. Glycogen biosynthesis in embryonic liver is wellcorrelated with the increase in the I/D ratio, i.e. the increase of the active form of enzyme. The proportion of granular glycogen in embryonic liver is increased from 15% up to 90% of total glycogen content between the 8th and 14th days of development. The activity of glycogen synthetase contained in granular glycogen is increased from 40% in the 8-day-old embryos up to 90% in the 18-day-old ones. The activity of phosphorylase is found in granular glycogen only on the 12th day of embryogenesis and reaches its maximum (80% of total enzyme activity) only on the 19th days of development. It is concluded that in the adult chicken liver the embronic enzymes--glycogen phosphorylase and glycogen synthetase--are retained.

[Changes in glycogen metabolism in chick embryo liver in relation to the formation of glycosomes]. / Izmeneniia obmena glikogena v pecheni kurinogo zarodysha v sviazi s formirovaniem glikosom.

In the chick embryo liver the portion of granular glycogen increases from 15 to 90% of the total content during the period from the 8th till the 14th days of developments. The activity of glycogen synthetase (KF 2.4.1.11) localized in the fraction of granular glycogen increases from 40 to 90% of the total activity in the 18 days old embryo. The activity of phosphorylase (KF 2.4.1.1) is detected in the granular glycogen of the liver only on the 12th day of development (10% of the total activity) and increase up to 80% on the 19th day of development. The maximal activation of glycogen synthetase and phosphorylase is noted after the glycosomes of formation in the developing embryoliver. A suggestion is put forward to the effect that the process of glycosome formation is a factor of the control of glycogen synthetase and phosphorylase activity.

[Changes in the characteristics of several carbohydrate metabolism enzymes during differentiation of loach skeletal muscle]. / Izmenenie kharakteristik nekotorykh fermentov uglevodnogo obmena v protsesse differentsirovki skeletnykh myshts v'iuna.

The gradual change of enzymes of glycogen metabolism proceeds during the skeletal muscle differentiation in the loach. The portion of the muscle type phosphorylase in the skeletal muscles of the embryo at the stage of the beginning of movement amounts to 30% and that at the stage of hatching to slightly over 50%. At the stage of yolk resorption, the skeletal muscles contain the muscle type phosphorylase only. At the same time the value of KM(UDPG) for glycogen synthetase gradually increases from 0,1 X 10(-3) up to 0,57 X 10(-3) M. The activity of alpha-glycerophosphate dehydrogenase increases more than 70 times.

[Characteristics of the activity of "satellite" enzymes of gluconeogenesis in the oocytes and embryos of loach]. / Osobennosti aktivnosti "satellitnykh" fermentov gliukoneogeneza v ootistakh i zarodyshakh v'iuna

The activity of "satellite" enzymes related to gluconeogenesis has been measured in the oocytes and embryos at the early stages of loach (Misgurnus fossilis L.) embryogenesis. The activity of pyruvate dehydrogenase increase during oocyte maturation by 30%, remains constant at the cleavage and blastula stages and decreased on the onset of gastrulation. In the both oocytes and embryos pyruvate dehydrogenase has been found only in the active form. The activity of citrate synthase, malate dehydrogenase and pyruvate carboxylase remained constant during oocyte maturation and et all early stage of embrional development. Citrate lyase and "malic"-enzyme were not found, Oocyte maturation is followed by a considerable increase in the malate and oxalacetate content, the level of pyruvate and acetyl-CoA being found invariable.

[Correlation of active and inactive forms of phosphorylase and glycogen synthetase in the liver of the developing chick embryo]. / Sootnoshenie aktivnoi i neaktivnoi form fosforilazy i glikogensintetazy v pecheni razvivaiushchegosia zarodysha kuritsy.

The marked changes in the activity and ratio of the active and inactive forms of glycogen synthetase and phosphorylase were found in the liver of developing chick embryo. The activity of phosphorylase increased in the liver from the 8th day of incubation till the end of embryogenesis. The practically complete activation of the inactive form of this enzyme was noted in the end of embryogenesis. The activity of glycogen synthetase in the liver increased till the 17th day of incubation and sharply decreased more than 6 times thereafter. The maximum of the active form of glycogen synthetase (1/3 of total activity) was noted on the 17th day as well. The changes in the content of glycogen synthetase in the liver are synchronized with those in the activity and ratio of the active and inactive forms of glycogen synthetase. The role of changes in the concentration of glucose and glucose-6-phosphate in the control of ratio of the active and inactive forms of enzymes of glycogen metabolism is discussed.