The secondary structure of bovine αs-casein and chemically modified α_s-casein in various solvents was investigated by infrared absorption spectrum and optical rotatory dispersion measurements. Amino groups of α_s-casein were either succinylated or acetylated, and carboxyl groups were either methylated or ethylated. Acetylated- and ethylated-α_s-caseins are insoluble in water. Water-soluble samples have unordered structure in water. In organic solvents, such as 2-chloroethanol and ethylene glycol, they have about 50% α-helical fraction. On the other hand, it was found that methylated-α_s-casein had two infrared absorption peaks centered at 1625 and 1643 cm^-1 in D₂O-CH₃OD mixed solvent. This fact may be connected with the presence of β-structure. In the case of solid film of this sample, cast from solution containing CH₃OH, the presence of β-structure was indicated, too. The authors attempted to explain the formation of β-structure in methylated-α_s-casein in terms of the electrostatic interactions due to the differences in the net charge between methylated and unmodified α₃-caseins.

View full abstract

Several 3, 5-dialkyl-4-hydroxybenzylidenemalononitriles and related compounds were tested for their fungicidal and acaricidal activities. The influence of structural variation on biological activity was studied by preparing and using a total of 22 compounds of benzylidenemalononitrile analogues.
Amongst the compounds tested 3, 5-di-tert-butyl and amyl-4-hydroxybenzylidenemalononitrile were most effective against fungus, Piricularia oryzae Car. and mite, Tetranychus telarius L.

View full abstract

The cells of_??_strain of Streptomyces sp. grown in a medium consisted of peptone, glucose and inorganic salts had little activity of urate degradation. The activity, however, was considerably promoted if the cells were incubated potassium phosphate buffer containing MgCl₂ and glucose, even in the absence of urate. Uricase activity of the cells was also significantly increased during the incubation without urate. The cells were shown to possess the activities of metabolizing adenine, guanine, hypoxanthine to urate. The incuba-tion with these purines caused an acceleration of urate breakdown by the cells and a remarkable increase of uricase activity in the cells. However, the amounts of uricase produced differed considerably with the kind of purines added to the incubation mixture even in the same molar concentration, and was largest with hypoxanthine. The induced formation of uricase by the endogenously generated urate was discussed.

View full abstract

Two kinds of α-glucosidase which were homogeneous in disc electrophoretic and ultra-centrifugal analysis were isolated from rice seeds by means of ammonium sulfate fractionation and CM-cellulose, Sephadex G-100 and DEAE-cellulose column chromatography and desig-nated as α-glucosidase I and α-glucosidase II.
Both α-glucosidases hydrolyzed maltose and soluble starch to glucose and showed same optimal pH (4.0) on the both substrates. In addition, both enzymes acted on various c-linked gluco-oligosaccharides and soluble starch but little or not on α-linked hetero-glucosides and α-l, 6-glucan (dextran).
Activity of the enzymes on maltose and soluble starch was inhibited by Tris and erythritol. α-Glucosidase II was more sensitive to the inhibitors than α-glucosidase I.
Km value for maltose was 1.1 mm for α-glucosidase I and 2.0mM for α-glucosidase II.

View full abstract

An enzyme, comenic aldehyde dehydrogenase, which catalyzes the oxidation of comenic aldehyde to comenic acid was partially purified from cell extract of Arthrobacter ureafaciens K-1.
The enzyme was purified 31-fold at Sephadex G-100 filtration step, 112-fold at DEAE-Sephadex A-50 fractionation step, and recovery of the activity was 73.30% and 38.5%, respectively.
NADP and magnesium ion were essential for the oxidation. The enzyme shows optimum activity at pH 7.8. Enzyme activity was extremely sensitive to sulfhydryl reagents such as p-chloromercuribenzoate and monoiodoacetate. L-Cysteine or dithiothreitol protected the enzyme from p-chtoromercuribenzoate inhibition. Carbonyl reagents, such as hydroxylamine and semicarbazide, inhibit the enzyme reaction by formation of addition compounds between carbonyl reagents and aldehyde group of the substrate. The enzyme was completely inactivated after heating for 5 min at 40°C. The Km for 5-methoxy comenic aldehyde is 2.5×10^-6 M, and for NADP is 0.4×10^-6 M. The reaction product, 5-methoxy comenic acid was identified by paperchromatography. The characterization of the enzyme has been carried out by using 5-methoxy comenic aldehyde as the substrate in stead of comenic aldehyde.

View full abstract

Microorganisms which produced n-alkane ω, ω'-dicarboxylic acid (DC) from n-alkane were selected from natural sources. It was found that the best three producers thus obtained belonged to yeast. All of the stock cultures which are able to assimilate n-alkane and are belonged to genus Candida and Pichia were also found to produce DC from n-alkane.
Candida cloacae 310, a representative strain selected from natural source, was able to produce DCs having 5 to 16 carbon atoms from various n-alkanes. Among them, DCs with 5 to 9 carbon atoms were more heavily accumulated than those with more than 9, except those with the same number of carbon atoms as the substrates which were the main products from the substrates with less than 15 carbon atoms. It was also clearly demonstrated that DCs with odd carbons alone were produced from n-alkanes with odd carbons, while DCs with even carbons alone from n-alkanes with even carbons.
Then, cultural conditions of Candida cloacae 310 were studied for the production of DC-12 from n-dodecane (n-C₁₂) which showed the highest yield among the observed accumulation.
Under the optimum conditions, 2.28g/liter of DC-12 was obtained together with 1.86g/liter of DC-6 and 0.82g/liter of DC-8 after 72hr' cultivation in a synthetic medium containing 100ml of n-C₁₂ per liter.

View full abstract

Decarboxylation of about twenty kinds of α, β and γ-amino acids in the reaction with glyoxal or ninhydrin was investigated. The decarboxylation rate of amino acids proved that steric and polar effects had important roles in the reaction.
From the data of pK₂ values and decarboxylation rates of amino acids, it can be con-cluded that under a similar steric environment, the decarboxylation rate depends on the anion concentration of amino acids.
Besides carbon dioxide, acetaldehyde, 2-propanone and propionaldehyde were respec-tively detected from the reaction of β-alanine, β and γ-amino-n-butyric acids with glyoxal or ninhydrin. The decarboxylation mechanism of these amino acids seemed to take place through the corresponding β- or γ-keto acid.
Oxygen absorption was also observed from the reaction of amino acids with dicarbonyl compounds.

View full abstract

L-Alanine adding enzymes from Bacillus subtilis and Bacillus cereus which catalyzed L-alanine incorporation into UDPMurNAc were partially purified and the properties of the enzymes were examined. The enzyme from B. subtilis was markedly stimulated by reducing agents including 2-mercaptoethanol, dithiothreitol, glutathione and cysteine. Mn²⁺ and Mg²⁺ activated L-alanine adding activity and their optimal concentrations were 2 to 5mM and 10mM, respectively. The optimum pH was 9.5 and the Km for L-alanine was 1.8×10^-4M. L-Alanine adding reaction was strongly inhibited by p-chloromercuribenzoate and N-ethyl-maleimide. Among glycine, L- and D-amino acids and glycine derivatives, glycine was the most effective inhibitor of the L-alanine adding reaction. The enzyme from B. cereus was more resistant to glycine than that from B. subtilis. Glycine was incorporated into UDPMurNAc in place of L-alanine, and the Ki for glycine was 4.2×10^-3 M with the enzyme from B. subtilis. From these data, the growth inhibition of bacteria by glycine is discussed.

View full abstract

A sulfur-containing peptide, acting as an enzymatic precursor of the aroma-bearing substance, was isolated in crystalline form from fruiting bodies of the shiitake mushroom. The isolation procedure consists of methanol extraction, repeated ion-exchange chromatographies, and crystallization from methanol-water. The common name “lentinic acid” is given for the isolated peptide. Amino acid analysis, performed after acid hydrolysis of the oxidized or desulfurized peptide, indicates involvement of a glutamic acid and S-sub-stituted cysteine sulfoxide in the molecule. Results of enzymatic assays led to the designa-tion of L-configuration for the component amino acids. The presence of a r-glutamyl peptide bond is shown, since glutamic acid constitutes the N-terminal amino acid and a free amino group is adjacent to a free carboxyl group. The structure proposed for lentinic acid is,
CH₃SO₂-[C₃H₆O₂S₂]-S(O)CH₂CH(COOH)NHCOCH₂CH₂CH(NH₂)COOH.
The precise structure for the portion in brackets is unidentified.

View full abstract

Protein fraction, prepared from fresh fruiting bodies of shiitake mushroom, is found capable of converting lentinic acid to lenthionine, the principal aroma-bearing substance of the mushroom. A simple Michaelis-Menten kinetics is also valid for the reaction. The reaction products identified, besides lenthionine and unidentified compounds, are glutamic acid, pyrubic acid, acetaldehyde, ammonia, and formaldehyde. Two different kinds of enzyme are envisaged to participate in the reaction; γ-glutamyl transpeptidase removing glutamyl moiety from lentinic acid, and pyridoxal phosphate dependent S-alkyl-L-cysteine sulfoxide lyase acting next on the resultant intermediate to produce an unstable inter-mediate which is then converted spontaneously to polythiepanes. A reaction pathway is proposed for lenthionine evolution from lentinic acid based on the experimental evidences obtained in this and other papers.

View full abstract

Mutants resistant to 1, 2, 4-triazolealanine (TRA) or 2-thiazolealanine (TA) were derived from Corynebacterium glutamicum ATCC-13761 by mutagenic treatment with N-methyl-N'-nitro-N-nitrosoguanidine. More than eighty percent of these mutants were found to accumulate a large amount of L-histidine in culture broth. Among these histidine producers, KY-10260 which was selected on TRA-containing agar, was used to investigate the cultural conditions for histidine production. The amount of histidine accumulation reached to a level of 6_??_8mg/ml with a medium containing 15% molasses (as glucose) and 4.5% ammonium sulfate.
According to the similar procedure, some histidine producers were derived from other bacteria, Arthrobacter citreus, Brevibacterium favum, Bacillus megaterium, Bacillus subtilis and Nocardia globerula.

View full abstract

Fifteen strains of bacteria were treated with ultraviolet light or N-methyl-N'-nitro-N-nitrosoguanidine to derive auxotrophic mutants, which were screened for their ability to produce L-threonine. A number of auxotrophs were derived from each strain. Among them, those which produced a large amount of L-threonine were found in Aerobacter aerogenes, Serratia marcescens and Escherichia coli, the members of the family Enterobacteriaceae. Nutritional requirements of these threonine producers were proved to be methionine, lysine, or α, ε-diaminopimelic acid (DAP).
In A. aerogenes and E. coli, double and triple auxotrophs were derived with futher mutational treatment. As α rule, imposition of additional block led to the increase of L-threonine production. In E. coli, many triple auxotrophs (DAP-, Met-, De-) and their isoleucine revertants were screened for their ability to produce L-threonine. Enhancement of L-threonine production was achieved with these mutants.
One of the isoleucine revertants, KY8280, was used to investigate some cultural con-ditions. As a result, L-threonine accumulation reached to a level of 13.8 m, g/ml with the medium containing 7.5% fructose.

View full abstract

D-Glucose and several alkyl-α-amino acids (glycine, DL-α-alanine, DL-α-amino-n-butyric acid, L-valine, L-leucine and DL-α-amino-n-caproic acid) were roasted at 200°C or 250°C in a simple two components system. From the roasting products were newly isolated a series of 2-(5-hydroxymethyl-2-formylpyrrol-l-yl)alkyl acid lactones which were characterized by elementary analysis, UV, IR, MS (GC-MS) and NMR spectra.
These lactones have characteristic aroma which may contribute to the flavor produced by sugar-amino acid reaction. The subjective evaluation of aroma of the lactones obtained were as follows: 2-(5-hydroxymethyl-2-formylpyrrol-l-yl)propionic acid lactone, caramel and a little scorching; -n-butyric acid lactone, maple and strong sweet; isovaleric acid lactone and isocaproic acid lactone, miso, soy sauce and a little chocolate-like.

View full abstract

Aromatic amino acids (phenylalanine, tyrosine and tryptophan) were heated at 300°C under nitrogen and volatile compounds generated were examined. Twelve compounds in which many of them have aromatic rings were identified in the volatiles from thermal degradation of phenylalanine. Tyrosine and tryptophan produced some phenols and indoles, respectively, besides several compounds. Formation mechanisms of some compounds were also discussed.

View full abstract

It has been elucidated that huratoxin, a piscicidal constituent of the sap of Hura crepitans, is a naturally occurring novel orthoester of a diterpene-hexaol with a 2, 4-tetradecadienoic acid. The diterpene-polyol (9) obtained by the acid hydrolysis of hexahydrohuratoxin was converted to an orthoacetate which held an important place in the structure argument. The results of some degradations of huratoxin, coupled with other chemical and spectral data lead to the structure I for huratoxin and its absolute stereostructure was established by X-ray analysis.

View full abstract