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Biomedical subjects

H Umezawa

Publications and source records attributed to H Umezawa.

At least 19 recordsLinked to original sources
PubMed1979

2-Amino-5-methyl-5-hexenoic acid, a methionine analog produced by Streptomyces sp. MF374-C4.

2-Amino-5-methyl-5-hexenoic acid (AMHA), a new methionine analog, was isolated from a fermentation broth of Streptomyces sp. MF374-C4 based on its reversal of the effect of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in a test system that determines the size of growth zones of revertants (His+) of Salmonella typhimurium TA1535. AMHA also inhibited growth of the tester strain in a synthetic medium. These AMHA activities were abolished by methionine. The incidence of spontaneous streptomycin-resistant mutations of Escherichia coli K12 was not decreased by AMHA at concentrations where cell growth was partially inhibited. AMHA inhibited protein synthesis but not DNA or RNA synthesis in S. typhimurium TA1535 and E. coli K-12. The analog inhibited formation of methionyl-tRNA but not of valyl-tRNA in a cell-free system of E. coli, and supported ATP-PPi exchange in the cell-free system. At concentrations where it inhibited cell growth, AMHA decreased the number of foci, induced by ROUS sarcoma virus, on cultured sheets of chick-embryo fibroblasts. The effects of AMHA on focus formation and on the cell growth were overcome by methionine.

Aminocaproates↗
PubMed1979

Studies on relationships between the structure and the glycosidase-inhibiting activity of HPAAO and its analogs.

p-Hydroxyphenylacetaldoxime (HPAAO) (anti and syn forms) obtained by fermentation and its analogs chemically synthesized were tested for their activities to inhibit various glycosidases. HPAAO inhibited bovine liver beta-galactosidase in a competitive manner at pH 7.0 with an apparent Ki value of 8 x 10(-8) M. HPAAO also inhibited various mammalian beta-glycosidases which had pH optima between 6.0 and 8.0. The syn form of HPAAO was found to be more active than the anti form against bovine liver neutral beta-galactosidase. It was concluded that the oxime moiety of HPAAO and its analogs was essential for their enzyme-inhibiting activity and the activities of aromatic or aliphatic oxime derivatives were dependent on the number of carbon atoms in their alkyl-chains.

Acetylglucosaminidase↗
PubMed1979

beta-Galactosidase-inhibiting new isoflavonoids produced by actinomycetes.

Six isoflavonoids having beta-galactosidase inhibiting activity were isolated from the culture filtrate of Streptomyces xanthophaeus. Their structures were determined by spectral analyses to be daidzein, daidzein 7-alpha-L-rhamnoside, daidzein 4',7-di-alpha-L-rhamnoside, genistein, genistein 7-alpha-L-rhamnoside and genistein 4',7-di-alpha-L-rhamnoside.

Actinomycetales↗
PubMed1979

Studies on auromomycin.

A new antitumor antibiotic, named auromomycin, was isolated from the culture broth of Streptomyces macromomyceticus, a macromomycin-producing strain. The antibiotic was recovered from the culture filtrate by salting out with ammonium sulfate and further purified by successive application of ion-exchange chromatography on Amberlite IRA-93 (Cl form) and DEAE-Sephadex (OH form), Gel filtration on Sephadex G-50 and hydrophobic chromatography on Octyl-Sepharose CL-4B. The antibiotic is an acidic polypeptide with a molecular weitht of 12,500 and an isoelectric point of pH 5.4 and consists of 16 different amino acids. It has characteristic absorption maxima at 273 nm and 357 nm in the ultraviolet spectrum and two minima at 280 nm and 350 nm in the optical rotatory dispersion spectrum. Auromomycin exhibits antibacterial activity not only against Gram-positive bacteria, but also Gram-negative bacteria. Antitumor activities of auromomycin were revealed against EHRLICH ascites carcinoma, ascites sarcoma 180, L1210 leukemia and LEWIS lung carcinoma. Auromomycin was found to be converted into macromomycin by adsorption chromatography on Amberlite XAD.

Amino Acids↗
PubMed1979

Biological studies on the degradation products of 3-[(S)-1'-phenylethylamino]propylaminobleomycin: a novel analog (pepleomycin).

Pepleomycin (PEP), 3-[(S)-1'-phenylethylamino]propylaminobleomycin has potent activity and is less pulmonary toxic than bleomycin (BLM). Biological activity and toxicity of the following degradation products of PEP have been studied in detail: the product of carbamoyl migration (ISO), the product of decarbamylation (DC), the product of ring closure of the side chain on the pyrimidine moiety (RC), the depyruvamide product (DP) and the product of an enzymatic inactivation (DA). These degradation products showed much lower activity than PEP in vitro: antimicrobial and anti-HeLa activities, inhibition of DNA synthesis in AH66 cells and the DNA strand cleavage. Acute toxicity and pulmonary toxicity were tested in mice. Results indicated much lower acute toxicity corresponding to the decreased in vitro activity when compared to PEP. DP and RC did not cause lung fibrosis in mice, while ISO and DC showed 1/2.6 and 1/5.7 degree of pulmonary toxicity, respectively, in comparison with PEP.

Animals↗
PubMed1979

Enzymatic conversion of aclacinomycin A to Y by a specific oxidoreductase in Streptomyces.

A specific oxidoreductase converting aclacinomycin A to a new analog, aclacinomycin Y, was purified to apparent homogeneity from the culture filtrate of aclacinomycin-producing microorganisms. The isolated enzyme was a weakly acidic protein (isoelectric point, 5.9) with a molecular weight of about 72,000. The enzymatic reaction requires molecular oxygen and has a pH optimum at 5.5. The enzyme catalyzed an oxidation of the terminal sugar, L-cinerulose, of the trisaccharide moiety of aclacinomycin A to L-aculose (2,3,6-trideoxyhex-2-enopyranos-4-ulose) with removal of two electrons. Studies of substrate specificity revealed that the enzyme is an oxidoreductase capable of modifying anthracyclic triglycosides by oxidizing their terminal sugars.

Aclarubicin↗
PubMed1979

Biosynthesis of leupeptin. II Purification and properties of leupeptin acid synthetase.

An enzyme which condenses acetyl-L-leucyl-L-leucine and L-arginine into acetyl-L-leucyl-L-leucyl-L-leucyl-L-arginine (leupeptin acid) was partially purified from a cell extract of Streptomyces roseus MA839-A1. With respect to this catalytic activity, the enzyme showed the following characteristics: ATP is essential; optimum pH is 9.5; the activity is inhibited either by EDTA or pyrophosphate or N-ethylmaleimide. The molecular weight of the enzyme is about 260,000 daltons. It also catalyzes some other extension reactions, such as, acetyl-L-leucine+L-leucine+L-arginine leads to leupeptin acid, and acetyl-L-leucine+L-leucine leads to acetyl-L-leucyl-L-leucine, but neither L-leucine+L-arginine leads to (L-leucyl)1--2-L-argining, nor acetyl-L-leucine+L-arginine leads to acetyl-L-leucyl-L-arginine. ATP-PPi exchange, catalyzed by this enzyme, proceeds with either acetyl-L-leucine, or acetyl-L-leucyl-L-leucine or L-leucine, but not with acetate or arginine.

Adenosine Triphosphate↗