PubMed Health⌕ Search

Biomedical subjects

H Weissbach

Publications and source records attributed to H Weissbach.

At least 253 records · Page 14Linked to original sources
PubMed1968

Effect of structural and stereochemical methylproline isomers on actinomycin biosynthesis.

The inhibitory effect of methylprolines on actinomycin biosynthesis by Streptomyces antibioticus was studied; the order of effectiveness was 3- >4- >5-methyl-dl-proline. Cis-3-methyl-dl-proline was 14 times more active than the trans isomer. It was also found that 4- and, possibly, 5-methylproline were incorporated into the actinomycin molecule. When 4-methylproline was present, three new actinomycins, representing 50 to 60% of the antibiotic mixture, were synthesized. Growth of the organism may be stimulated at concentrations (0.1 to 1.0 mug per ml) of 3-methylproline that inhibit antibiotic formation, thus providing additional evidence for a different mechanism of actinomycin synthesis from that of protein synthesis. Azetidine-2-carboxylic acid, piperdine-2-carboxylic acid, and hydroxyproline (but not sarcosine) reversed the inhibition due to 3-methylproline.

Chromatography, Paper↗
PubMed1967

Unusual growth characteristics of a methionine-cyano-B12 auxotroph of Escherichia coli.

Escherichia coli K-12, strain AB1172, substrain 2276, a methionine(-)-cyano-B(12) (-) auxotroph grew poorly when placed in a medium containing optimal levels of cyano-B(12) and suboptimal amounts of l-methionine. A marked depression of N(5,10)-methylene-H(4)-folate reductase was observed in the inhibited cells, although no significant alterations in other enzymes involved in the metabolism of N(5,10)-methylene-H(4)-folate were observed. Guanosine was effective in preventing the growth inhibition.

Adenine↗