Isolation,Structure and Physiological Activities of Piericidin B,Natural Insecticide Produced by a Streptomyces

Piericidin B was isolated from mycellia of Streptomyces mobaraensis besides piericidin A. On the basis of IR, NMR and mass spectral studies together with chemical evidences, its structure was assigned as Id. Its physiological activities are also deescribd.     

13C-NMR Spectra and Streochemistry of Isoechinulins A,B and C

¹³C-NMR spectra of isoechinulins A, B and C, metabolites from Aspergillus ruber, were fully assigned on the basis of chemical shifts and multiplicities and comparison with their analogues. Taking advantage of the symmetrical structure of the diketopiperazine ring, the stereochemistry of the trisubstituted carbon-carbon double bond in a dehydrotryptophyl moiety was determined as Z (cis) by measuring the coupling constants, , in the proton nondecoupled spectrum of isoechinulin B.     

Isolation and Structure Elucidation of Three New Insecticidal Cyclodepsipeptides,Destruxins C and D and Desmethyldestruxin B,Produced by Metarrhizium anisopliae

A multi-channel continuous-flow analyzer equipped with biosensing devices was developed for multi-component measurement and its use in automating routine analysis was evaluated.

Biosensing was achieved by the aid of an immobilized enzyme reactor installed in the channel, and the channel switching process for the sensing of a different compound was made by using a column-switching rotary valve. Another rotary valve was used for auto-sampling. Both of the two rotary valves were interfaced to a system controller and work conjugatively in a programmed manner. Signal subtraction between different channels was found to be more precise compared with the multi-channel flow-injection analysis method, which is of merit for an analysis utilizing enzyme relay reaction (as for sucrose analysis) or for background signal subtraction. Glucose, lactate, and sucrose content in real samples were measured automatically with high reproducibility, and the results agree well with the kit method.     

Effects of Phosphatidylcholine or Ergosteryl Oleate on Physiological Properties of Saccharomyces sake

Chromatographically homogeneous phosphatidylcholine identified by thin-layer chromatography on silica gel G was isolated from mycelia of Aspergillus oryzae or egg yolk by a combination of alumina and silicic acid column chromatography. Although the 2-position in both Asp. oryzae- and egg yolk-phosphatidylcholine was occupied nearly exclusively by unsaturated fatty acids, significant proportions of unsaturated fatty acids were also found in the 1 -position of Asp. oryzae-phosphatidylcholine. In nitrogen gas-sparging anaerobic culture of Saccharomvces sake Kyokai No. 7, supplementing the basal synthetic medium with phosphatidylcholine enhanced the yeast growth and fermentative activity, whereas adding ergosteryl oleate enhanced alcohol-endurability. Supplementation with both phosphatidylcholine and ergosteryl oleate promoted the yeast growth, fermentative activity and alcohol-endurability of cells.     

Simple Synthesis of (R)-5-Hexadecanolide

Chemical modification of tryptophan residues in abrin-a with N-bromosuccinimide (NBS) was studied with regard to saccharide-binding. The number of tryptophan residues available for NBS oxidation increased with lowering pH, and 11 out of the 13 tryptophan residues in abrin-a were eventually modified with NBS at pH 4.0, while 6 tryptophan residues were modified at pH 6.0 in the absence of specific saccharides. Modification of tryptophan residues at pH 6.0 greatly decreased the saccharide-binding ability of abrin-a, and only 2% of the hemagglutinating activity was retained after modification of 3 residues/mol. When the modification was done in the presence of lactose or galactose, 1 out of 3 residues/mol remained unmodified with a retention of a fairly high hemagglutinating activity. However, GalNAc did not show such a protective effect. NBS-oxidation led to a great loss of the fluorescence of abrin-a, and after modification of 3 tryptophan residues/mol, the fluorescence intensity at 345 nm was only 38% of that of the unmodified abrin-a. The binding of lactose to abrin-a altered the environment of the tryptophan residue at the saccharide-binding site of abrin-a, leading to a blue shift of the fluorescence spectrum. The ability to generate such fluorescence spectroscopic changes induced by lactose-binding was retained in the derivative in which 2 tryptophan residues/mol were oxidized in the presence of lactose, but not in the derivative in which 3 tryptophan residues/mol were oxidized in the absence of lactose. Importance of the tryptophan residue(s) in the saccharide-binding of abrin-a is suggested.     

Cell Structure of Yeasts Grown Anaerobically in Aspergillus orpzae-Proteolipid-supplemented Media

Effects of Aspergillus oryzae-proteolipid (PL) on the formation of high concentrations of alcohol, more than 20% as in sake brewing, have been studied. Electron microscopy revealed that there were no vacuoles but many lipid deposits in cytoplasm of the alcoholtolerant cells of Saccharomyces sake Kyokai No. 7, which were obtained by the anaerobic culture supplemented with PL. Sphaeroplasts from the alcohol-tolerant cells were stable in 20% alcohol, whereas those from the untolerant cells grown anaerobically in the PL-unsupplemented media were ruptured. The cell membrane became alcohol-endurable in the anaerobic cultures with PL. Synthetic phospholipid promoted yeast growth and the fermentative activity, whereas a small amount of sterol ester enhanced the alcohoi-endurability. The supplementation of both lipids anaerobically induced physiological properties characteristic of the alcohol-tolerant cells.     

Isolation and Biological Activity of a Peptidal Antibiotic P168

The structure of the xyloglucan synthesised in vitro by the particulate fraction of suspension-cultured soybean (Glycine max) cells from UDP-glucose and UDP-xylose is mainly composed of two kinds of oligosaccharide-building blocks, a heptasaccharide unit and a pentassaccharide unit [T. Hayashi and K. Matsuda, J. Biol Chem., 256, 11117 (1981)]. The synthesis of the pentasaccharide unit is probably the first step in the construction of oligosaccharide building blocks to elongate the ²-1,4-glucan backbone. This enzymatically synthesized xyloglucan was shown to have the same molecular size (M_w, 180,000) as the xyloglucan prepared from soybean cell walls by gel filtration on a Sepharose CL-6B column, and the same building blocks distributed among each fraction. A pulse-chase experiment indicated that the pentasaccharide unit was converted into the heptasaccharide unit. The conversion was regulated by the concentration of UDP-xylose.