Formation of Threonine Aldolase by Bacteria and Yeasts

Threonine aldolase was found to be formed in various strains of bacteria and yeasts when they were grown in media containing l-threonine as a sole source of carbon. As the other sources of carbon, d, l-allothreonine, l-serine and glycine were effective but glucose and sucrose were inert for the formation of the enzyme.

The maximal formation of the enzyme was observed in the initial of stationary phase of growth and, thereafter, the enzyme disappeared with the consumption of l-threonine. It seems that the enzyme is adaptive in nature and that it is responsible for the growth in threonine as the carbon source.     

A Growth Factor for Malo-lactic Fermentation Bacteria

A growth factor (TJF) for a malo-lactic fermentation bacterium has been isolated from tomato juice, and found to be a β-glucoside. The NMR spectra of TJF and its acetate revealed that the glucosyl residue linked to the hydroxyl group at C-2′ or C-4′ of d- or l-pantothenic acid moiety. Then, 2′-O-(β-d-glucopyranosyl)-dl-pantothenic acid (I), 4′-O-(β-d-glucopyranosyl)-dl-pantothenic acid (II) and 4′-O-(β-d-glucopyranosyl)-d(R)-pantothenic acid (II-a) were synthesized, and Il-a and 4′-O-(β-d-glucopyranosyl)-l-pantothenic acid (II-b) were obtained by the optical resolution of the acetate of II. Among the above compounds, II-a was identical with natural TJF regarding to the biological activity, NMR and ORD spectra, and thin-layer chromatography.     

Purification,Crystallization and Properties of Tryptophanase from Proteus rettgeri

An inducible tryptophanase was crystallized from the cell extract of Proteus rettgeri grown in a medium containing l-tryptophan. The purification procedure included ammonium sulfate fractionation, heat treatment, DEAE-Sephadex and hydroxylapatite column chromatographies. Crystals were obtained from solutions of the purified enzyme by the addition of ammonium sulfate.

The crystalline enzyme preparation was homogeneous by the criteria of ultracentrifugation and zone electrophoresis. The molecular weight was determined to be approximately 210,000.

The crystalline enzyme catalyzed the degradation of l-tryptophan into indole, pyruvate and ammonia in the presence of added pyridoxal phosphate. The enzyme also catalyzed pyruvate formation from 5-hydroxy-l-tryptophan, 5-methyl-l-tryptophan, S-methyl-l-cysteine and l- cysteine. l-, d-Alanine, l-phenylalanine and indole inhibited pyruvate formation from these substrates.     

Synthesis and Some Properties of UDP-(1)fructose

UDP-(1)fructose was synthesized essentially by the method of Michelson or Roseman et al. The product obtained was much more stable to acid than UDP-fructose isolated from Jerusalem artichoke tubers by Umemura et al.⁷⁾ and UDP-glucose. Hydrolysis time curves of UDP-(1)fructose and fructose-1-phosphate in 0.01N HGl and 0.1N HCl both at 100°C are presented. It was concluded from these curves that UDP-(1)fructose was first hydrolyzed into UMP and fructose-1-phosphate, and then fructose-1-phosphate was hydrolyzed more slowly into free fructose and inorganic phosphate.     

4-Hydroxy-β-damascone and 4-Hydroxy-dihydro-β-damascone from Cigar Tobacco

The cDNA encoding a putative xylose reductase (xyrA) from Aspergillus oryzae was cloned and coexpressed in the yeast Saccharomyces cerevisiae with A. oryzae xylitol dehydrogenase cDNA (xdhA). XyrA exhibited NADPH-dependent xylose reductase activity. The S. cerevisiae strain, overexpressing the xyrA, xdhA, endogenous XKS1, and TAL1 genes, grew on xylose as sole carbon source, and produced ethanol.     

γ-Irradiation Effects on the Antioxidative Activity Developing in the Amino Acid-Sugar Reaction

The effects of γ-irradiation on the antioxidative activity developing in the amino acid-sugar reaction were investigated. The antioxidative activity of the nondialyzable melanoidin prepared from glycine and d-glucose was not much affected by γ-irradiation. However, the development of the antioxidative activity of an l-leucine-d-glucose solution on heating was markedly accelerated when the mixture had been preirradiated with γ-rays, and the development of the activity was more prominent than that of the brown color. The irradiation of a glucose solution alone accelerated the antioxidative activity development when heated with leucine, but the irradiation of a leucine solution alone did not cause a similar effect when heated with glucose. Except an l-cysteine-glucose combination, all combinations of amino acids and sugars tested gave rise to almost similar antioxidative effects.     

Fermentation of C14-Labeled Cellobiose by Cellulomonas fimi

Crude cell-free extracts from Cellulomonas fimi contain cellobiose phosphorylase which cleaves cellobiose into glucose and glucose-1-phosphate in the presence of inorganic phosphate. With the aid of this enzyme, two samples of C¹⁴-cellobiose labeled in reducing or non-reducing glucosyl moiety were prepared from uniformly labeled C¹⁴-glucose or C¹⁴-glucose-1-phosphate as substrate, respectively. The labeled preparations have been shown to be radiochemically pure. Analyses of the anaerobic fermentation products from C¹⁴-cellobiose by resting cell suspensions showed that both glucose moieties were fermented almost equivalently. However, relatively small differences in specific activities of the products revealed that significantly larger amounts of formic acid and smaller amounts of acetic acid were produced from the reducing glucose moiety than from the other half of the molecule. Succinic and lactic acids appeared to be produced almost equally from both moieties.     

The Isolation and Characterization of the Acid-Soluble Nucleotides from the Tubers of Jerusalem Artichoke (Helianthus tuberosus L.)

The acid-soluble nucleotides were extracted from the tubers of Jerusalem artichoke with percbloric acid, and separated and purified by means of adsorption on and elution from active charcoal, repeated chromatography on columns of Dowex I (Cl^-), followed by paper chromatography. The following nucleotides have been characterized and/or identified: 5′-AMP, 3′-AMP, ADP, ATP, 5′-GMP, 2′-GMP, 3′-GMP, 2′,3′-cyclic GMP, GDP, GTP, 5′-UMP, UDP, UTP, NADP, UDP-glucose, UDP-galactose, UDP-fructose, UDP-N-acetylhexosamine and GDP-mannose.^** Neither cytosine ribonucleotides nor deoxyribonucleotides have been detected. The significance of these observations is discussed.