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Biomedical subjects

A Yoshimoto

Publications and source records attributed to A Yoshimoto.

At least 127 records · Page 7Linked to original sources
PubMed1980

Biosynthesis of anthracycline antibiotics by Streptomyces galilaeus. II. Structure of new anthracycline antibiotics obtained by microbial glycosidation and biological activity.

New anthracycline antibiotics derived from epsilon-, gamma- and beta-rhodomycinones and epsilon-isorhodomycinone by the microbial glycosidation using an aclacinomycin-negative mutant, the strain KE303, of Streptomyces galilaeus MA144-M1 were studied to elucidate their structures and biological activities. These antibiotics were the products in which the anthracyclinones added as precursors were linked at C-7 or C-10 position with the same trisaccharide moiety (cinerulosyl-2-deoxyfucosyl-rhodosaminyl group) as in the parental antibiotic aclacinomycin A. In addition to antimicrobial activity, they exhibited the growth inhibition of cultured L1210 leukemia cells and the marked inhibition against DNA and RNA synthesis.

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

Antitumor anthracycline antibiotics, aclacinomycin A and analogues. I. Taxonomy, production, isolation and physicochemical properties.

Aclacinomycin A and B, two major components of a new antitumor antibiotic complex, and their 19 analogues were produced by a culture of strain No. MA144-M1, which was identified as Streptomyces galilaeus. They were isolated by chelation with copper ion and silicic acid chromatography, and characterized by physicochemical methods in the anthracycline group of antibiotics.

Antibiotics, Antineoplastic↗
PubMed1978

Effect of guanosine 5'-diphosphate 3'-diphosphate and related nucleoside polyphosphates on induction of tryptophanase and beta-galactosidase in permeabilized cells of Escherichia coli.

Exogenous addition of guanosine and adenosine 5'-(mono, di and tri) phosphate 3'-diphosphates (pppGpp, ppGpp, pGpp, pppApp, ppApp and pApp) stimulated the synthesis of tryptophanase and beta-galactosidase in permeabilized cells of Escherichia coli. From the results obtained with ppGpp and pppApp, this effect appeared to be at a transcriptional level and depended greatly on the growth condition; the largest effect was observed in cells under shiftdown or grown on poor enrgy source. ppGpp and pppApp, unlike cyclic AMP, did not act to overcome the inhibition of enzyme induction by glucose, but in combination with cyclic AMP caused a synergistic stimulation effect. In the shiftdown cells, ppGpp and pppApp gave 30% or more stimulation effect on tryptophanase induction while cyclic AMP did not stimulate induction. There was therefore a pronounced difference between cyclic AMP and ppGpp or pppApp in stimulatory function.

Adenine Nucleotides↗
PubMed1976

Enzymatic synthesis of poly-beta-hydroxybutyrate in Zoogloea ramigera.

The enzyme activity synthesizing poly-beta-hydroxybutyrate (PHB) was mainly localized in the PHB-containing particulate fraction of Zoogloea ramigera I-16-M, when it grew flocculatedly in a medium supplemented with glucose. On the other hand, the enzyme activity remained in the soluble fraction when the bacterium grew dispersedly in a glucose-starved medium. The soluble PHB synthase activity became associated with the particulate fraction as PHB synthesis was initiated on the addition of glucose to the dispersed culture. Conversely, the enzyme activity was released from the PHB-containing granules to the soluble fraction when the flocculated culture was kept incubated without supplementing the medium with glucose. PHB synthase was also incorporated into the newly formed PHB fraction when partially purified soluble PHB synthase was incubated with D(-)-beta-hydroxybutyryl CoA in vitro. Although attempts to solubilize the particulate enzyme were unsuccessful, and the soluble enzyme became extremely unstable in advanced stages of purification, both PHB synthases had the same strict substrate specificity for D(-)-beta-hydroxybutyryl CoA, and showed the same pH optimum at 7.0.

Coenzyme A Ligases↗
PubMed1976

Occurrence of pppApp-synthesizing activity in actinomycetes and isolation of purine nucleotide pyrophosphotransferase.

The occurrence of adenosine 5'-triphosphate-3'diphosphate-synthesizing activity was detected in five strains of actinomycetes; Streptomyces morookaensis, Streptomyces aspergilloides, Streptomyces hachijoensis, tactinomyces violascens and Streptoverticillium septatum, out of 825 strains of actinomycetes, bacteria, fungi and fungi imperficti. Purine nucleotide pyrophosphotransferase were extracellularly excreted associating with the cell growth, and were purified partially or to apparent homogeneiety from the culture filtrate. The enzymes are a monomeric protein with molecular weight of 18,000-26,000 and synthesize adenosine, guanosine and inosine 5'-phosphate (mono, di or tri)-3'-diphosphate such as pApp, ppA pp, pppApp, pGpp, ppGpp, pppGpp, and pppIpp by transferring a pyrophosphoryl group from the 5'-position of ATP, dATP and ppApp to the 3'-position of purine nucleotides in the presence of a divalent cation and in alkaline state.

Actinomycetales↗
PubMed1975

Purine nucleotide pyrophosphotransferase from Streptomyces morookaensis, capable of synthesizing pppApp and pppGpp.

Purine nucleotide pyrophosphotransferase was purified to apparent homogeneity from a culture filtrate of Streptomyces morookaensis. It is a monomeric protein with a molecular weight of 24 000-25 000, and its isoelectric point is 6.9. The enzyme synthesizes purine nucleoside 5'-phosphate (mono, di, or tri) 3'-diphosphates such as pppApp, ppApp, pApp, pppGpp, ppGpp and pppIpp by transferring a pyrophosphoryl group from the 5'-position of ATP, dATP and ppApp to the 3'-position of purine nucleotides. The purified enzyme catalysed the formation of 435 mumol of pppApp and 620 mumol of pppGpp from ATP and GTP per min mg protein under the standard conditions. The enzyme requires absolutely a divalent cation for activity, and optimum pH for the enzyme activity lay above 10 for Mg2+, for Co2+ and Zn2+ from 9 to 9.5, and for Fe2+ from 7.5 to 8. The following Michaelis constants were determined: AMP, 2.78 mM; ADP, 3.23 mM; GMP, 0.89 mM; GDP, 0.46 mM and GTP, 1.54 mM, in the case of ATP donor. The enzyme is inhibited by guanine, guanosine, dGDP, dGTP, N-bromosuccinimide, iodacetate, sodium borate and mercuric acetate.

Adenosine Triphosphate↗