Characteristics of carbohydrate metabolism in the rat liver in thiamine deficiency

Thiamine deficiency in rats induced by oxythiamine is accompanied by an increase in the free NADP+/NADPH ratio in liver tissue, which results in multifold stimulation of the metabolite flux in the oxidation branch of the pentose cycle. The increase in the intracellular concentrations of isocitrate and alpha-ketoglutarate with a simultaneous decrease of malate in the liver of vitamin-deficient rats points to the inhibition of alpha-ketoglutarate dehydrogenase responsible for the anomalous metabolism under conditions of thiamine deficiency. The decrease of the functional activity of the tricarboxylic acid cycle is concomitant with the activation of conversions in the oxidation branch of the pentose cycle, glucuronate and glycolytic pathways of carbohydrate metabolism, which is directed at eliminating the energy deficiency in rats with B1-hypovitaminosis.     

Investigation of the enzymic and electrochemical oxidation of uric acid derivatives.

The electrochemical oxidation of a number of N-methylated uric acids at the pyrolytic graphite and gold electrodes has been compared to their enzymic oxidation with type VIII peroxidase and H2O2. Spectral, electroanalytical and kinetic evidence supports the conclusion that for all compounds the electrochemical and enzymic reactions proceed by identical mechanisms.     

Chemical synthesis of a tetradecamer in the deoxyribonucleic acid series

The chemical synthesis of a tetradecadeoxyribonucleotide, d-EtSp(A-T-G-G-A-A-A-C-T-G-C-G-G-C), is described. This oligomer, designated Fragment 4δ, constitutes the 5′-terminus of the plus strand of a projected duplex coding for S-Peptide_2–14 derived from Ribonuclease A. The Fragment was constructed by block condensation via a phosphorothioate anchor. Complications due to inadvertent phosphotriester condensations are discussed. Arguments justifying the sequence selection are presented.