Ikunori Koshiyama

A new enzyme, proline acylase (N-acyl-l-proline amidohydrolase) from Pseudomonas species

Abstract A new enzyme, proline acylase, extracted from a strain of Pseudomonas species has been purified to apparent homogeneity and has been shown to hydrolyze specifically N- acyl - l - proline derivatives such as N- acetyl - l - proline and chloroacetyl- l -proline. N -Acetylamino acids other than l -proline were unsusceptible, or nearly so. The enzyme also hydrolyzed the carboxyterminal proline residue in a peptide when its penultimate position was occupied by a glycine, such as Z-Gly- l Pro and Z-Gly- l Pro- l Leu-Gly- l Pro. It has a pH optimum at pH 6.0 and was inhibited by chelating reagent. The molecular weight was estimated to be 597 000 and 623 000 by sedimentation equilibrium and gel filtration, respectively. Upon disc electrophoresis in 1% SDS, the purified preparation migrates as a single band of molecular weight 55 000. The sedimentation coefficient and isoelectric point, determined by polyacrylamide gel electrophoresis, were s 20, w 0 = 18 S and pH = 5.0, respectively.

Oxidative Browning of Amadori Compounds from Amino Acids and Peptides

The oxygen-dependent browning (oxidative browning) of Amadori compounds from amino acids or peptides was studied since it was an important reaction contributing to the discoloration and deterioration of some foodstuffs containing sugars and amino compounds during storage in contact with atmospheric oxygen.

Studies on Osmophilic Yeasts:Part XI. Various Factors Affecting on Polyalcohol Production by Pichia miso

Various conditions were studied which gave influences on polyalcohol production by Pichia miso. Pichia miso gave an excellent yield of polyalcohol showing good growth in the vitamin-free medium. Unlike Zygosaccharomyces high concentrations of phosphate such as 2% as KH2PO4 in the medium showed no detrimental effect on polyalcohol production. Remarkable reduction in polyalcohol yield was observed in the medium of high concentration of nitrogen sources, among which yeast extract showed the most striking effect. Polyalcohol fermentation was provoked in the medium of 0.1% yeast extract while the metabolic activity distinctly converted to ethanol fermentation when the organisms were incubated in the medium of 4.0% yeast extract. The fact that a large amount of ethanol more than 6% in the medium was produced aerobically by genus Pichia of oxidative dissimilation type seemed to be very interesting and noticeable. For the purpose of industrial production, it was shown that polyalcohol production in jar-fermenter ...

Studies on Soybean Protein: Part I. A Ribonucleoprotein and Ribonucleic Acids in Soybean Casein Fraction

Soybean casein fraction was factionated by gel filtration with Sephadex G100. From the effluent diagram of soybean casein fraction, several minor components were obtained with a main component.One of them showed a single pattern by ultracentrifugal analysis, but it was found to be contaminated with RNA by column chromatography on DEAE-cellulose. From the result of purification by the repeated rechromatography, the purified component contained about 7% of RNA per protein. Therefore, it was considered to be a ribonucleoprotein.Among other minor components, free ribonucleic acids, which seemed to have different molecular weights were also present, but their ratios of purine to pyrimidine and base compositions coincided well each other.