Judgement of sunstruck flavor of beer has been relying on the sensory evaluation. However, this sensory test is inaccurate, as well known. Utilizing the experimental result that sunstruck flavor is caught completely with silver nitrate, the authors established a potentiometric method for the determination of sunstruck flavor substance of beer by expressing its intensity in the amount of silver ions combined with it.

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The reduction of streptomycin with aluminum amalgam to dihydrodesoxystreptomycin (α-hydroxyaldehyde to monohydric alcohol, in its streptose moiety) is reproduced at dropping mercury electrode and at controlled-potential mercury pool electrode. The accompanying formation of dihydrostreptomycin, of which α-hydroxyl group is intact, depends upon the cathode potential and pH. Electrolysis at a potential corresponding to the relatively negative part of polarographic reduction wave and at relatively higher pH favors the formation of dihydro derivative and vice versa. This explains, from polarographic standpoint, the characteristic mode of reduction with aluminum amalgam. Electroreduction of streptomycin is applicable for the preparation of dihydrodesoxyderivative but not so for that of dihydro derivative.

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Browning of green broad bean appears only in the seed-coat, and not in cotyledon. This phenomenon coincides with the facts that phenolic compounds such as L-tyrosine and 3, 4- dihydroxyphenylalanine are localized in the seed-coat tissues. But little is known about the browning mechanism of the seed-coat at present.
In this study, the presence of dopa-O-β-D-glucoside was confirmed in addition to those phenolic compounds mentioned above, and the distribution of this substance in tissues of green broad bean was examined by paper chromatography. A clear indication of the relationships between the mechanism of brown pigmentation and the biosynthesis of dopa-O-β-Dglucoside in vivo was also presented.

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The influences of some environmental physical conditions during irradiation upon the survival of bacteria were investigated. This report deals with the effect of the secondary ray from the metallic foil and the influence of the irradiation in frozen state on survivals of bacteria.

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Inactive protease in the cell free extracts obtained from growing cells of Aspergillus sojae KS was collected in a supernatant of ultracentrifugation at 14×10⁴g, and in fractions obtained by acetone of 35-50 per cent and by ammonium sulfate of 0.5-0.6 saturation.
The inactive protease has the same resistance against pH or heat treatments as active protease has. The activation of the inactive protease was maximal between pH 5-6, and was accelerated by several kinds of protease, and was not affected by thioglycollate and KCN.

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Microbial dehydrogenations of 3β-hydroxyl groups of Digitalis cardiac agiycones by Calonectria decora and Nigrospora sphaerica were studied, both of which exhibited simiiar transformation pattern. Digitoxigenin was transformed exclusively into 3-dehydrodigoxigenin by C. decora and into digoxigenin and 3-dehydro-digoxigenin by N. sphaerica. Both gitoxigenin and 3-acetyl-gitoxigenin were dehydrogenated to 3-dehydrogitoxigenin. 3-Dehydro-16-acetylgitoxigenin was also detected among the bioconversion products of 16-acetylgitoxigenin and 3, 16-diacetylgitoxigenin by these two species.

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The presence of glucose-6-phosphate markedly stimulated the anaerobic utilization of glyoxylate by either cell-free extracts or partially purified enzyme preparations of coli-aerogenes bacteria. The enzymic reduction of glyoxylate to glycollate was found to occur in the presence of TPN with the following substrates; glucose-6-phosphate, glucose plus ATP, gluconate plus ATP, glucose-1-phosphate or malate. The data indicated that the reduction of glyoxylate to glycollate was coupled to the oxidation of glucose-6-phosphate via the hexose monophosphate shunt pathway. It was propounded that the operation of the hexose monophosphate oxidative pathway might be controlled by TPN-linked glyoxylic reductase, and the mechanisms of enzymic regulation in microbial respiration were also discussed.

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The enzyme was purified approximately 20-times in specific activity as judged by the rate of casein hydrolysis. The rate was depressed considerably with increasing substrate concentration. Analyzing this phenomenon according to the Lineweaver and Burk equation, it wassuggested that an inactive complex consisting of one molecule of enzyme and five molecules of substrate was formed.
The effects of various materials on the enzymatic activity were examined and it was found that Cu⁺⁺, Mn⁺⁺ and some reducing agents stimulated the rate of the reaction, but Hg⁺⁺ and Ag⁺ inhibited it strongly and some sulfhydryl group binding reagents inhibited it slightly.

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Tissue extracts of healthy, sliced and black-rotted sweet potato roots of several Japanese varieties showed immunochemical precipitation lines with antisera toward sliced and diseased tissue extracts prepared from an American resistant variety, Sunnyside. The immunochemical precipitation patterns of healthy and sliced tissue extracts and those of diseased tissue extract of the Japanese varieties respectively were almost the same as those of sliced and diseased tissue extracts of the American Sunnyside. Antigenic components designated as A and Cs were distributed in all tissue extracts of both Japanese and American varieties. Components B and D were produced in response to the infection in root tissues of Japanese varieties as well as of American ones. The amount of component B produced in several Japanese varieties was correlated with the magnitude of resistance action of root tissues to the fungus infection and the order was as follows: Norin No.10 (highly resistant)>Norin No.1 and Okimasari (resistant)>Norin No.4 and Norin No.5 (susceptible). Components B and D seemed to be present in healthy root tissue in very small amounts, and showed an increase in response to the simple injury or slicing, though the magnitude of this increase was much less than the response to the pathogenic infection.

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In investigating the properties of the dehydrogenating system from ammonia to nitrate, it has been observed that DPN is reduced with urea also in the presence of an enzyme from fowl liver. The properties of the enzyme are very closely similar to those of ammonium dehydrogenase. However, some fundamental differences have been demonstrated by comparing these two enzymes, especially concerning reducion of TPN, substrate inhibition, formation of some nitrogenous metabolites and reoxidation of DPNH in the reaction mixture. The reaction was postulated to be a dehydrogenation of urea by an enzyme. This activity has also been demonstrated in silkworm and yeast.

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It was found that the purified chitinase preparation acts upon glycol chitin resulting in the decomposition to constituent aminosugar, the saccharifying activity being determined by application of the Morgan-Elson reaction. The enzymatic properties of the mold chitinase were investigated by measuring liquefying activity and saccharifying activity. Distinct differences were observed between the two activities, and especially liquefying activity was more stable than saccharifying activity against heat treatment. The chitinase preparation whose saccharifying activity was inactivated by heating was able to decrease the viscosity of glycol chitin solution, with an insignificant production of aminosugar.

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Nucleotide-peptide linkages were detected in a ribonucleic acid preparation obtained from yeast. Adenosine-3'-phosphate combined with dinitrophenylated peptide was isolated after digesting the dinitrophenylated ribonucleic acid with enzymes. The peptide consisted of nine kinds of amino acid. In this preparation one peptide may be linked to the phosphate of terminal adenylic acid through its amino terminal, serine, as phosphoamide.

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Inactivation of crystalline enzyme, Streptomyces protease G, by γ-ray irradiation in an aqucous system has been investigated.It is indicated that inactivation of the enzyme is attributable mainly to the indirect action of radiation. The inactivation curve is exponential and the G-vaiue for enzyme inactivation is calculated as 0.1 at an enzyme concentration of 1×10^-5M, which is not infnuenced by varying pH. Effects of various other solutes on radiation inactivation have been also studied. Halogen ions, especially iodine ion, and nitrite ion are most protectivc among various inorganic anions examined, and alkali mctal and alkali earth metal cations arc ineffective. Among various organic compounds examined, sulfur-containg compounds and unsaturated compounds are generally effective for protection of enzyme activity against radiation damages. The protective effect of benzene is enhanced by the substitution of electron donating groups. Chloroform and chioral are found to act as a synergist for irradiation inactivation.

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