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.     

L-Tyrosine production by Polyauxotrophic Mutants of Corynebacterium glutamicum

Polyauxotrophic mutants of Corynebacterium glutamicum which have additional requirements to L-phenylalanine were derived from L-tyrosine producing strains of phenylalanine auxotrophs, C. glutamicum KY 9189 and C. glutamicum KY 10233, and screened for L-tyrosine production. The increase of L-tyrosine production was noted in many auxotrophic mutants derived from both strains. Especially some double auxotrophs which require phenylalanine and purine, phenylalanine and histidine, or phenylalanine and cysteine produced significantly higher amounts of L-tyrosine compared to the parents, A phenylalanine and purine double auxotrophic strain LM–96 produced L-tyrosine at a concentration of 15.1 mg per ml in the medium containing 20% sucrose. L-Tyrosine production by the strain decreased at high concentrations of L-phenylalanine.     

Activation of Nrf2/Keap1 signaling and autophagy induction against oxidative stress in heart in iron deficiency

We investigated the effects of dietary iron deficiency on the redox system in the heart. Dietary iron deficiency increased heart weight and accumulation of carbonylated proteins. However, expression levels of heme oxygenase-1 and LC3-II, an antioxidant enzyme and an autophagic marker, respectively, in iron-deficient mice were upregulated compared to the control group, resulting in a surrogate phenomenon against oxidative stress.     

DNA as a Flocculation Factor in Pseudomonas sp.

A component responsible for flocculation was extracted from Pseudomonas strain C-120 by treating the cells with 3 M guanidine hydrochloride. The guanidine hydrochloride-extracted cells were reflocculated, not only with the guanidine hydrochloride extract but with DNA prepared from various bacteria. The reconstituted flocs were deflocculated by deoxyribonuclease or guanidine hydrochloride which indicated that the reconstituted flocs closely resembled natural flocs. In reconstitution experiments using Escherichia coli DNA at different molecular weights, it was found that DNA with a molecular weight higher than about 6 × 10⁶ was required to flocculate the guanidine hydrochloride-extracted cells. Heat-denatured DNA did not flocculate the guanidine hydrochloride-extracted cells. DNA with a high molecular weight was detected in the guanidine hydrochloride extract. It was concluded that the component involved in flocculation of this organism was highly polymerized double stranded DNA.     

Colorimetric determination of fructose for the high-throughput microtiter plate assay of glucose isomerase

A colorimetric method for the reducing monosaccharide determination is optimized for the assay of glucose isomerase, which converts glucose (Glc) to fructose (Fru). Test solution was mixed with 20-fold volume of the 50 mM Na₂SiO₃, 600 mM Na₂MoO₄, and 0.95 M HCl aqueous solution (pH 4.5), in which a yellow molybdosilicate species was formed. The mixture was kept at 70 °C for 30 min. Test solution containing 10 mM level Fru gave a remarkable blue reaction mixture, in which the Mo(VI) species was reduced by Fru to form a blue molybdosilicate species. The blueness increased with the Fru concentration. Glc cannot render the reaction mixture blue as strong as Fru. Thus, the colorimetric method can be used advantageously for the determination of 10 mM level Fru in the Glc isomerase reaction mixture, even in the presence of 100 mM level Glc, and has been applied successfully to the microtiter plate assay of the enzyme.     

Late-maturing cooking rice Sensyuraku has excellent properties,equivalent to sake rice,for high-quality sake brewing

Low protein content and sufficient grain rigidity are desired properties for the rice used in high-quality sake brewing such as Daiginjo-shu (polishing ratio of the rice, less than 50%). Two kinds of rice, sake rice (SR) and cooking rice (CR), have been used for sake brewing. Compared with those of SR, analyses of CR for high-quality sake brewing using highly polished rice have been limited. Here we described the original screening of late-maturing CR Sensyuraku (SEN) as rice with low protein content and characterization of its properties for high-quality sake brewing. The protein content of SEN was lower than those of SR Gohyakumangoku (GOM) and CR Yukinosei (YUK), and its grain rigidity was higher than that of GOM. The excellent properties of SEN with respect to both water-adsorption and enzyme digestibility were confirmed using a Rapid Visco Analyzer (RVA). Further, we confirmed a clear taste of sake produced from SEN by sensory evaluation. Thus, SEN has excellent properties, equivalent to those of SR, for high-quality sake brewing.     

Purification and Properties of a Pectate Lyase in Erwinia aroideae

A strain of Erwinia aroideae produced an extracellular pectolytic enzyme under growth conditions with pectin or pectic acid as the inducer. This strain also produced a pectin lyase when nalidixic acid is added to a culture medium. The pectolytic enzyme produced under the growth conditions was purified approximately 40-fold from the culture fluid by carboxy- methyl cellulose and Sephadex G-75 gel column chromatographies. The purified enzyme was almost homogeneous on sodium dodecyl sulfate polyacrylamide gel electrophoresis, having a molecular weight of about 36,000 to 38,000. This enzyme, with optimal activity at pH 9.0 to 9.2, produced reaction products which had a strong absorption at 230 nm indicating a lyase type of the reaction. The enzyme activity was markedly stimulated by calcium ion and completely inhibited by cobalt and mercuric ions and by ethylenediaminetetraacetate. Pectic acid or pectin with lower methoxyl content was a good substrate for this enzyme, while no significant activity was observed when pectin with higher methoxyl content was used as a substrate. It was concluded that the enzyme produced under the normal growth conditions is an endo-pectate lyase and differs from the pectin lyase induced by nalidixic acid.