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A L DEMAIN

Publications and source records attributed to A L DEMAIN.

At least 19 recordsLinked to original sources
PubMed1965

EXCRETION AND DEGRADATION OF RIBONUCLEIC ACID BY BACILLUS SUBTILIS.

Demain, A. L. (Merck & Co., Inc., Rahway, N.J.), R. W. Burg, and D. Hendlin. Excretion and degradation of ribonucleic acid by Bacillus subtilis. J. Bacteriol. 89:640-646. 1965.-Bacillus subtilis MB-1480 was found to produce several 5'-ribonucleotides in the extracellular medium, in addition to the previously found 5'-guanosine monophosphate and guanosine diphosphate. The nucleotides accumulated after excretion of high-molecular-weight ribonucleic acid (RNA) and subsequent extracellular breakdown. Excretion of RNA paralleled growth closely, and was accompanied by deoxyribonucleic acid (DNA) and protein excretion. The process occurred in the absence of visible lysis. Whereas extracellular DNA was stable, the other macromolecules were degraded after excretion. With extracellular DNA as a measure of maximal lysis, it was calculated that the major part of the extracellular RNA must have been excreted by cells which had not undergone lysis.

Bacillus subtilis↗
PubMed1964

NUTRITION OF "ADENINELESS" AUXOTROPHS OF YEASTS.

Demain, Arnold L. (Merck Sharp & Dohme Research Laboratories, Division of Merck & Co., Inc., Rahway, N.J.). Nutrition of "adenineless" auxotrophs of yeasts. J. Bacteriol. 88:339-345. 1964.-Nutritional studies on 29 "adenineless" yeast strains were carried out. In no case could guanine, xanthine, or their ribonucleosides or ribonucleotides be used to satisfy the purine requirement. The cultures fell into three nutritional groups: group A, absolute purine requirement satisfied by adenine or hypoxanthine; group B, stimulatory purine requirement (leaky) satisfied by adenine or hypoxanthine; group C, absolute purine requirement satisfied only by adenine. Although adenosine, adenylic acid (AMP), inosine, and inosinic acid (IMP) could not be used by the absolute mutants, the leaky mutants were stimulated by these compounds. The rapid growth on adenine observed with members of all three nutritional groups was delayed by guanine. No inhibition was observed with guanosine or guanylic acid (GMP). Guanine and its derivatives did not inhibit growth of wild-type Saccharomyces cerevisiae. The slow growth of the leaky mutants in unsupplemented medium was inhibited by guanine, guanosine, and GMP. The results were interpreted as follows. (i) Yeasts lack GMP-reductase. (ii) Group A and B yeasts are blocked before IMP; group C yeasts lack one of the enzymes leading from IMP to AMP. (iii) The absolute mutants cannot take ribonucleotides or ribonucleosides into the cell and cannot break down these compounds extracellularly to the free base; the leaky mutants can slowly use extracellular nucleosides and nucleotides. (iv) Guanine competes with adenine for entry into the cell. (v) Guanine inhibits de novo synthesis of AMP. The inhibition is probably a weak feedback effect which can only be demonstrated with leaky strains which synthesize purines at suboptimal rates.

Adenine↗
PubMed1964

PRODUCTION OF EXTRACELLULAR GUANOSINE-5'-MONOPHOSPHATE BY BACILLUS SUBTILIS.

Demain, A. L. (Merck Sharp & Dohme Research Laboratories, Rahway, N.J.), I. M. Miller, and D. Hendlin. Production of extracellular guanosine-5'-monophosphate by Bacillus subtilis. J. Bacteriol. 88:991-995. 1964.-Wild-type Bacillus subtilis colonies were found to feed purineless mutants. A strain with high feeding capacity was selected for study, with a guanineless mutant of B. subtilis used as the assay organism. The factor was excreted during its growth phase in a complex medium containing starch and soybean meal extract. Nutritional studies led to the development of a defined medium to be used for biochemical studies and to aid in the isolation of the factor. Starch was replaced by maltose and the soybean meal extract by Mn(++). Production of the factor was sensitive to the pH of the medium during growth. Practically its entire extracellular accumulation occurred before visible lysis. The factor was identified as guanosine-5'-monophosphate derived by extracellular enzymatic hydrolysis of excreted ribonucleic acid.

Bacillus subtilis↗
PubMed1963

Nonbiological conversion of cephalosporin C to a new antibiotic by sodium thiosulfate.

The apparent stimulation of cephalosporin C biosynthesis by sodium thiosulfate is due to a nonbiological conversion of cephalosporin C to a new derivative, cephalosporin C(x). The new compound is more active than cephalosporin C against the assay organism, Escherichia coli W-208. Cephalosporin C(x) retains the properties of ultraviolet absorption and resistance to penicillinase, but migrates more slowly than cephalosporin C in the paper-chromatographic system used.

Anti-Bacterial Agents↗
PubMed1963

Effect of methionine, norleucine, and lysine derivatives on cephalosporin C formation in chemically defined media.

Demain, A. L. (Merck Sharp & Dohme Research Laboratories, Rahway, N.J.), Joanne F. Newkirk, and D. Hendlin. Effect of methionine, norleucine, and lysine derivatives on cephalosporin C formation in chemically defined media. J. Bacteriol. 85: 339-344. 1963.-Chemically defined media were developed for production of cephalosporin C by Cephalosporium sp. In such media, the requirement for methionine can be satisfied by norleucine. Further stimulation of antibiotic production was obtained with the lysine derivatives epsilon-N-acetyl-l-lysine and epsilon-aminocaproic acid but not with lysine itself. Also inactive were alpha-aminoadipic and ketoadipic acids. Other lysine derivatives were found to inhibit cephalosporin C production at 0.01 m. The final medium supported the production of approximately 0.5 g of cephalosporin C per liter of medium.

Acremonium↗
PubMed1962

Biosynthesis of cephalosporin C.

The superiority of d-methionine over l-methionine for stimulation of cephalosporin C synthesis in a crude medium was confirmed. The optimal level of dl-methionine was 0.5%. Methionine stimulates growth slightly but this is not thought to be the cause of the marked stimulation of antibiotic synthesis. Of a large number of sulfur compounds tested, only dl-methionine-dl-sulfoxide and S-methyl-l-cysteine showed considerable methionine-replacing activity. Lysine and alpha-aminoadipic acid were inactive.

2-Aminoadipic Acid↗