[Biosynthesis of NADP-malate dehydrogenases in greening etiolated maize leaves]. / Biosintez NADP-malatdegidrogenaz pri zelenenii etiolirovannykh list'ev Kukuruzy.

The activities of NADP-dependent malate dehydrogenases in greening etiolated maize leaves were studied. "Malic" enzyme (EC 1.1.1.40) in bundle sheath cells developed slower as compared to NADP-malate dehydrogenase synthesizing malic acid in mesophyll chloroplasts. The increase in "malic" enzyme activity in the light was suppressed by protein synthesis inhibitors--chloramphenicol and cycloheximide. Possible localization of enzyme protein synthesis is discussed.

[Effect of phosphorylation on glycolysis in the cells of assimilating millet leaf tissues]. / Vlianie fotofosforilirovaniia na reaktsii glikoliza v kletkakh assimiliatsionnykh tkanei list'ev prosa.

The effect of phosphorylation on glycolysis reactions was studied in respect with the rate of 1-14C-glucose metabolization and the composition of synthesized labelled products in isolated cells of assimilating millet leave tissues incapable to reassimilation of respiratory CO2. Data on oxygen metabolism in mesophyll protoplasts and in cells of parenchymal facing of vascular bundle sheaths in the absence and in the presence of electron acceptors (3,5-dichlorophenolindophenol and methylviologen) show that they retain adenylate pool and energy charge characteristic of photosynthetizing tissues. The glycolysis rate decreased in illuminated cells, which did not remove carbon products from chloroplasts. Analysis of compounds produced from 1-14C-glucose exogenous ADP effect on their ration and the change of adenylate energy charge in the presence of methylviologen demonstrates that the acting factor is a decrease of Pi and ADP concentrations in cytoplasm because of their use chloroplast phosphorylation. It is suggested, that a short-cut chain of glycolysis reactions may take place in intact cells assimilating CO2 in photosynthesis, and the capacity of this chain is determined by the type of carbon metabolism and photorespiration mechanism.

[Reversibility of glycolysis in leaves of C4-plants]. / Issledovanie obratimosti glinkoliza v list' iakh C4-rastenii.

A conversion of the reaction of two cytoplasmic glycolysis enzymes, phosphoglycerate mutase and phosphopyruvate hydratase, is necessary for sucrose synthesis from pyruvate in leaves of C4-plants in the light, when phosphoenolpyruvate synthesis from pyruvate and phosphoglycerate reduction can be carried out by chloroplasts. Leaves of C4-plants differ from those of C3-plants in a higher activity of cytoplasmic glycolysis enzymes, which are distributed irregularly in two assimilatory tissues. The ratio of pyruvate kinase and enolase reaction activities is high in parenchyma linings of vascular fascicles (where mitochondria are concentrated), and it is low in mesophyl tissue, where phosphoglucerate in equilibrium phosphoenolpyruvate reaction is included into photosynthetic metabolism. The data obtained on isolated mesophyl protoplasts have shown that the reaction equilibrium is sharply shifted into the direction of phosphoenolpyruvate formation from phosphoglycerate. However, the incorporation of 14C into sugars is not completely inhibited in the atmosphere of N2-A possibility of incorporation of tri-carbon fragments into sugars in photosynthesizing leaves via conversion of enolase reaction and via alternative pathways is discussed.

[Malic acid induction of decarboxylating NADP-malate dehydrogenase synthesis in C3-plant leaves]. / Induktsiia sinteza NADP-malatdegidrogenazy (dekarboksiliruiushchei) v list'iakh C3-rastenii iablochno-56i kislotoi.

The activity of decarboxylating NADP-malatedehydrogenase (E. C. 1.1.1.40) in green ethiolated pea and barley leaves and in green leaves of a pea mutant lacking photosystem II is found to be 3-fold increased after the injection of malic acid into cut plants. Protein synthesis inhibitors depressed malic acid-induced increase of the activity of "malic"-enzyme, the effect of chloramphenicol being more pronounced in ethiolated green leaves, and that of cycloheximide--in leaves of a mutant with formed photosynthetic apparatus. Possible dependence of malate-induced biosynthesis of "malic"-enzyme on the degree of NADP reduction in chloroplasts is discussed.

[Study of properties of NADP malate dehydrogenase from corn leaves]. / Issledovanie svoistv NADP-malatdegidrogenazy iz listev kukuruzy.

Kinetic properties of purified chloroplast isoenzyme of the "malic" enzyme from corn leaves were studied. The enzyme had optimum activity at pH 8.0 and 36 degrees C. Under standart conditions the Michaelis constants for the "malic" enzyme with Mn2+ as cofactor are 0.091 mM for malate and 0.04 mM for NADP. In case of Mg2+ as cofactor they are 0.66 and 0.02 mM respectively. Respective Km values for the cofactors Mn2+ and Mg2+ are 0.018 and 0.091 mM. The activity of the "malic" enzyme was inhibited by reduced NADP and NAD, ATP, ADP, fructose-1,6-diphosphate, oxaloacetic, oxalic, glyoxylic, glycolic and alpha-ketoglutaric acids, as well as by phosphate anions and pyrophosphate. The inhibitory effect of all metabolites and ions is more pronounced in case of Mn, rather than Mg, used as cofactors for the reaction. A possibility of metabolic regulation of NADP-"malic" enzyme activity in the leaves of C4-plants, is discussed.

[Isolation and purification of NADP-dependent "L-malate"-enzyme from corn leaves]. / Vydelenie i ochistka NADP-zavisimogo "malik"-enzima iz list'ev kukuruzy

Isolation and purification of "malic-enzyme" NADP was done using fractionation by ammonium sulfate, anion-exchange chromatography on DEAE cellulose, gel-filtration through Sephadex G-200 and purification on DEAE Sephadex A-50. The isoenzyme isolated had a specific activity of 40-50 mkM/mg protein per min (approximately 80-fold purification) and contained negligible admixtures.