A New Method for Estimation of the Mycelial Weight in Koji

A New method was devised for the estimation of the mycelial weight in rice-koji. In this method, the content of glucosamine in koji was used for the calculation of mycelial weight. The content of glucosamine in the mycelia of Aspergillus oryzae, koji, and rice was determined by a colorimetry after hydrolysis of these materials with sulfuric acid and purification of glucosamine fraction with a Dowex 50 W column. And the values of glucosamine were 114.5 mg/g in mycelia, 3.03 in the koji for amazake,* 1.34 in the koji for sake, and 0.0 in rice. The mycelial contents calculated from these data were 2.6% dry weight in amazake-koji and 1.2% in sake-koji.     

Distribution of Nuclease O Inhibitor among Aspergillus Species

Leucine dehydrogenase was inhibited by p-chioromercuribenzoate and HgCl₂, but not by 5,5′-dithiobis(2-nitrobenzoic acid), 4,4′-dithiopyridine and N-ethylmaleimide. Modification of sulfhydryl groups of the enzyme with p-chloromercuribenzoate and HgCl₂ was accompanied with a loss of the enzyme activity. The 6 reactive sulfhydryl groups per enzyme molecule play an essential role for catalysis. Approximately 12 sulfhydryl groups were titrated per molecule in the presence of 8 m urea: the enzyme contains 2 sulfhydryl groups per subunit, and one of them participates in the catalytic action. Fluorometric and gel filtration studies on binding of NADH to the enzyme revealed that the enzyme contains 6 coenzyme binding sites per molecule.

These results are compatible with the hexameric structure of leucine dehydrogenase composed of identical subunits, showing that each subunit has one catalytic site and one indispensable sulfhydryl group.     

Production of 5′-dRiboflavin-α-d-glucopyranoside in Growing Cultures by the Mold Mucor

During the investigations on riboflavin glycoside formation by Aspergillus, Mucor, Penicillium and Rhizopus, a remarkable production of 5′-d-riboflavin-α-d-glucopyranoside was observed in several strains belonging to the genus Mucor when grown on a, medium containing maltose and riboflavin. Several conditions on 5′-d-riboflavin-α-d-glucopyranoside formation were also investigated with washed mycellium of M. javanicus. Maltosyl compounds such as maltose, dextrin, amylose and soluble starch were the effective glucosyl donor, whereas glucose, fructose, sucrose, lactose and dextran were inactive.     

The Isomerization of Alkyl Phosphorothionates Induced by Carboxylic Acid Amides

Alkyl phosphorothionates are isomerized to phosphorothiolates by the catalytic action of dimethylformamide. Methyl parathion (O,O-dimethyl O-p-nitrophenyl phosphorothionate) and sumithion (O,O-dimethyl O-3-methyl-4-nitrophenyl phosphorothionate) are more reactive than ethyl parathion (O,O-diethyl O-p-nitrophenyl phosphorothionate). Saligenin cyclic methyl phosphorothionate (salithion) decomposed to give a complicated pattern of products on thin layer chromatography. Besides S-methyl isomer, desmethyl sumithion (O-methyl O-3-methyl-4-nitrophenyl hydrogen phosphorothioate), 3-methyl-4-nitrophenol, methyl formate and dimethylamine were detected as reaction products from sumithion. Some other carboxylic amides including dimethylacetamide, acetamide and urea are also active. A reaction mechanism is proposed.     

Binding of Polysaccharide to Peptidoglycan in Cell Wall of Streptomyces roseochromogenes

The polysaccharide-peptidoglycan complex, which was prepared with lysozyme from Streptomyces roseochromogenes IAM53 cell walls, was hydrolyzed with lytic enzyme of Flavo-bacterium to separate polysaccharide. The enzymatically prepared polysaccharide (100 mg) contained 500 μmoles of hexoses, 40 μmoles of hexosamines and 31 μmoles of phosphate. Hexoses consisted of mannose and galactose in a molar ratio of 5 to 1. Hexosamines consisted of equimolar glucosamine and muramic acid, a half of which was identified as muramic acid 6-phosphate. The reducing end of the polysaccharide was muramic acid. The polysaccharide extracted with trichloroacetic acid contained no muramic acid-phosphate. So the polysaccharide moiety of S. roseochromogenes cell walls must be linked covalently to 6-position of muramic acid in peptidoglycan through phosphate,     

Generation of the antioxidant yellow pigment derived from 4-methylthio-3-butenyl isothiocyanate in salted radish roots (takuan-zuke)

2-[3-(2-Thioxopyrrolidin-3-ylidene)methyl]-tryptophan (TPMT) is a yellow pigment of salted radish roots (takuan-zuke) derived from 4-methylthio-3-butenyl isothiocyanate (MTBITC), the pungent component of radish roots. Here, we prepared salted radish and analyzed the behavior of the yellow pigment and related substances in the dehydration process and long-term salting process. All salted radish samples turned yellow, and their b^* values increased with time and temperature. The salted radish that was sun-dried and pickled at room temperature turned the brightest yellow, and the generation of TPMT was clearly confirmed. These results indicate that tissue shrinkage due to dehydration, salting temperature, and pH play important roles in the yellowing of takuan-zuke.     

Enzyme-Substrate Complex of p-Hydroxybenzoate Hydroxylase; One of the Activated Intermediates of the Overall Reaction

The transglucosidation reaction of brewer’s yeast α-glucosidase was examined under the co-existence of l-sorbose and phenyl-α-glucoside. As the transglucosidation products, three kinds of new disaccharide were chromatographically isolated. It was presumed that these disaccharides consisting of d-glucose and l-sorbose were 1-O-α-d-glucopyranosyl-l-sorbose ([α]_D+89.0), 3-O-α-d-glucopyranosyl-l-sorbose ([α]_D+69.1) and 4-O-α-d-glucopyranosyl-l-sorbose ([α]_D+81.0). The principal product formed in the enzyme reaction was 1-O-α-d-glucopyranosyl-l-sorbose.