Purification and Properties of Penicillin Acylase from Kluyvera citrophila

Penicillin acylase (EC 3.5.1.11) of Kluyvera citrophila KY7844 was purified approximately 120-fold by DEAE-cellulose chromatography, hydroxyapatite chromatography and isoelectro-focusing fractionation. The purified enzyme, with an approximate molecular weight of 63,000, appeared to be homogeneous in disc electrophoretic analysis, and showed isoelectric point (Ip) 8.12 and 13.0 units/mg of specific activity for cephalexin hydrolysis. The Michaelis constant (Km) for cephalexin and for 7-[1-(1H)-tetrazolylacetamido]-desacetoxycephalosporanic acid ((1H) T-7ADCA) was 1.4 mM and 3.6 mM, respectively. This enzyme was capable of producing (1H) T-7ADCA in 80% yield from 1-(1H)-tetrazolylacetate methylester and 7-aminodesacetoxycephalosporanic acid.     

Studies on the Formation of Uricase by Streptomyces

The cells of a 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 incubation 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.     

Studies on the Changes of Meat Fats by Various Processings

Data are presented to show the gas chromatographic identification of a total of 18 saturated aliphatic γ- and δ-lactones obtained from melted beef depot fat, namely, δ-C₆, γ-C₇, γ-C₈, γ-C₉, and a homologous series of γ- and δ-lactones of the even-carbon numbers C₁₀ to C₁₆ and of smaller amount of the odd-carbon numbers C₁₁ to C₁₅. These lactones were isolated by steam distillation and silicic acid adsorption chromatography, and identified through gas chromatography and infrared spectroscopy.

Lactones obtained had a peach-like flavor, and it was suggested that lactones were important in heated beef fat as the flavor compounds.     

Inhibition of malaria parasite growth by quinomycin A and its derivatives through DNA-intercalating activity

Quinomycin A and its derivatives were identified as potent antimalarial (Plasmodium falciparum) agents in a screen of the RIKEN NPDepo chemical library. IC₅₀ values of quinomycin A and UK-63,598 were approximately 100 times lower than that of the antimalarial drug chloroquine. This activity was mitigated by the addition of plasmid DNA, suggesting that these compounds act against parasites by intercalating into their DNA.     

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.     

Antitumor Activity of an Alkali Extract of Clostridium saccharoperbutylacetonicum Cells

Bacillus thuringiensis var. israelensis produces 130-kDa proteins which are toxic to mosquito larvae. The ISRH4 gene encoding 1,180 amino acids of the 130-kDa insecticidal protein was fused with lac Z′ on a plasmid, pUC19, and sequentially deleted from the C-terminus to construct a series of deletion mutants. All the deletion mutant genes directed the production of truncated ISRH4 proteins fused with the α-complementing fragment of β-galactosidase in Escherichia coli cells in the presence of isopropyl β-d-thiogalactopyranoside. Analysis of the mosquito larvicidal activity of deletion mutant proteins revealed that the N-terminal 29 amino acids and the C-terminal 485 amino acids could be removed without loss of the activity.     

Volatile Components of Roasted Almonds: Basic Fraction

Roasted almond volatiles were isolated by vacuum carbon dioxide distillation of acetone extracts and separated into basic and non-basic fractions. The basic fraction was analyzed by combination gas chromatography-mass spectrometry utilizing open tubular column. Seventeen pyrazines and 2-formyl pyrrole were identified by comparison of their mass spectra with reference spectra. Besides them, five compounds were tentatively identified by mass spectrometry.     

Comparison of Extracellular Polysaccharide Produced by Pullularia pullulans with Polysaccharides in the Cells and Cell Wall

The purified swep hydrolase appeared homogeneous on SDS disc electrophoresis, and the molecular weights of the enzyme and the subunit were 280,000 and 70,000, respectively. The isoelectric point of this enzyme was pH 4.8.     

Structural Uniformity of Pullulan Produced by Several Strains of Pullularia pullulans

Extracellular polysaccharides produced by 3 strains of Pullularia pullulans were fractionated by treating with cetyl trimethyl ammonium hydroxide into soluble and insoluble fractions, and the structure of the former fraction, i.e., pullulan, was studied. The yield and the ratio of 2 fractions varied widely according to the strains. But the structure of pullulan was found to be uniform irrespective of the strains used. All 3 samples of pullulan gave only glucose on complete acid hydrolysis, and 93~95% maltotriose and 5~7% maltotetraose after isoamylase (pullulanase) action. The ratio of α-1,4- to α-1,6-glucosidic linkages calculated from periodate oxidation data coincided very well with the value expected from the ratio of maltotriose to maltotetraose units. An evidence for the complete absence of branch structure in pullulan was presented from the results of hydrolysis by pullulan 4-glucanohydrolase.