N-Carboxymethyl-l-serine,a New Acidic Amino Acid from Asparagus (Asparagus officinalis) Shoots

A strongly acidic amino acid—N-carboxymethyl-L-serine—, not previously known in nature, has been isolated from asparagus (Asparagus officinalis) shoots. Some unique properties of this amino acid, such as a much bigger mobility to anode on high voltage paper electrophoresis (pH 3.6) than aspartic acid and characteristic changes of NMR spectra in aqueous solution with various pD, were discussed in relation to its structure.     

Purification and Properties of an S-PI(Pepstatin Ac)-insensitive Carboxyl Proteinase from a Xanthomonas sp. Bacterium

A S-PI(Pepstatin Ac)-insensitive carboxyl proteinase was found in culture filtrate of a Xanthomonas sp. bacterium. The carboxyl proteinase was highly purified and about 100 mg of the enzyme was obtained from 601 of culture filtrate, with a recovery of 25%. The optimum condition for the action of the purified enzyme toward casein was approx. pH 2.7 and its activity was not inhibited by any of such carboxyl proteinase inhibitors as Pepstatin, S-PI, and DAN but EPNP inhibited it. Such behavior of the enzyme against inhibitors resembles that of Pseudomonas sp. carboxyl proteinase, the first found from a bacterium. Some differences were observed, however, in their properties such as optimum pH, isoelectric point, and amino acid composition.     

Effect of Heavy Metal Ions on the Growth and Iron-oxidizing Activity of Thiobacillus ferrooxidans

Effect of heavy metal ions on the growth and the iron-oxidizing activity of Thiobacillus ferrooxidans were investigated.

Cupric, zinc, cadmium, and chromium ions had no effect on the growth and the iron-oxidizing activity of cell suspensions or cell-free extracts of the bacterium in high concentrations (10^?3~10^?2M). Lead ion delayed the start of the growth slightly in 10^?3 M, but it did not inhibit the iron-oxidizing activity of the cells in the concentration. Tin and molybdenum oxide ions inhibited both of them in the concentration above 10^?3 M.

Mercuric mercurous, and silver ions had the most harmful effect. In the concentration of 10^?3 .M, each of the cations inhibited almost completely both the growth and the iron-oxidizing activity of the cells.

In the experiments with cell-free extracts it was observed that the activity of cytochrome oxidase (cytochrome a₅₉₇) operating in the iron-oxidizing system of the bacterium was specifically inhibited with mercuric ion in the concentration above 5 × 10^?4 M.     

Selection of High Ubiquinone 10-Producing Strain of Tobacco Cultured Cells by Cell Cloning Technique

A novel enzyme, which was named N^α-benzyloxycarbonyl amino acid urethane hydrolase, was purified from a cell-free extract of Streptococcus faecalis R ATCC 8043, using N^α-benzyloxycarbonyl glycine as substrate. The enzyme was purified 1300-fold with an activity yield of 8%. The purified enzyme was homogeneous by disc electrophoresis. The molecular weight of the native enzyme is about 220,000 by gel filtration, and a molecular weight of 32,000 was determined for the reduced and denatured enzyme by gel electrophoresis in sodium dodecyl sulfate. The isoelectric point was 4.48. The enzyme was inhibited by p-chloromercuribenzoate. The presence of divalent cations (i.e., Co²⁺ or Zn²⁺) is essential for its activity.     

Applying Proteolytic Enzymes on Soybean

Soy proteins were incubated with a microbial acid protease (Molsin) under the following condition: substrate concentration, 1%; enzyme-substrate ratio (by weight), 1/100; pH, 2.8; and temperature, 40°C—flavor components and related impurities are removable from crude soy-protein concentrates by their incubation for 2 hr under the above condition. The acid-precipitated fraction of soy protein incubated for 2 hr with Molsin (i.e. 2 hr-proteolyzate) showed the following composition: 10% trichloroacetic acid (TCA) insoluble fraction, 47.52%; 10% TCA soluble peptide fraction, 52.02%; and free amino acid fraction, 0.46%. Gel filtration of the 2 hr-proteolyzate gave an elution pattern showing its molecular weight distribution.

In the process of the incubation of the acid-precipitated protein, the 10% TCA insoluble fraction showed increase in amino nitrogen content, its solubility in a phosphate buffer increased to change at 6 hr, and a hydrophobic amino acid share in this fraction increased gradually.

In vitro digestibility of the acid-precipitated fraction were improved and the lipoxygenase activity in this fraction decreased through the Molsin treatment.

Ultracentrifugal analysis showed a decreasing tendency of the cold-insoluble fraction of soy protein during its incubation with Molsin. Optical rotatory dispersion and circular dichroism study elucidated conformational changes in this fraction during its incubation either with or without Molsin.     

δ-Hydroxylysine,Canavanine and Three α-Amino Acid Amides from Ladino Clover Seed (Trifolium repens L. var. giganteum)

The antibacterial effects of salivary nitrate/nitrite on the growth of three Desulfovibrio species were examined. The bacteria did not grow on plates with ≥0.2 mM nitrate or ≥1.0 mM nitrite. They were also incubated in filter-sterilized saliva. D. desulfuricans was reduced on the order of >10² compared with the control solution (phosphate-buffered saline) in nine out of the 10 participants.     

Isolation and Identification of Ubiquinone 10 from Cultured Cells of Tobacco

Callus tissues were induced from stem and root segments of Rauwolfia serpentina. Growth and alkaloid production of the callus tissues were examined under various culture conditions. The growth was strikingly promoted in the presence of 2,4-D (0.5~1 ppm), kinetin (0.2~0.5 ppm) and yeast extract (0.1~0.2%). At favourable conditions, the growth value in 4 weeks’ culture was ca. 40 (F.W.), and ca. 25 (D.W.) for stem callus tissues, and ca. 15 (F.W.), and ca. 8 (D.W.) for root callus tissues. Stem and root callus tissues produced ajmaline and some other unidentified Rauwolfia alkaloids. The ajmaline content in root callus tissues was 10~20mg % and in stem callus tissues was 1~10mg %. The ajmaline production was strikingly reduced when 2,4-D concentration increased, or kinetin was omitted in the culture medium. Phytosterols including stigmasterol, β-sitosterol or cholesterol were also produced.     

Differences in NMR Spectra between Some α- and γ-Glutamyl Dipeptides

A methanol-utilizing phototrophic bacterium, strain M402, was isolated from surface water of an acidic hot spring. The isolated strain was identified as Rhodopseudomonas acidophila from its morphological and physiological characters. Profiles of the utilization of non-aromatic compounds as carbon sources by this strain were in good agreement with those of some strains of R. acidophila reported by Pfennig [J. Bacteriol., 99, 597 (1969)]. However, strain M402 was found to be capable of utilizing vanillic acid, vanillin, vanillyl alcohol, ferulic acid, veratric acid, syringic acid, syringal-dehyde and benzyl alcohol as carbon sources under anaerobic-light conditions. Although Pfennig did not refer to these abilities of his strains, these notable characters of strain M402 seem to be additional new characters of R. acidophila.     

Ng-Methylated Arginines in Broad Bean Seed

l-N^g-Methylarginine, l-N^g,N^g-dimethylarginine and ethanolamine were isolated from basic amino acids fraction of broad bean (Vicia faba L.) seed. The presence of N^g,N′^g-dimethylarginine was also suggested.