English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Tryptophan oxygenase (tryptophan 2,3-dioxygenase) activity increases immediately before the initiation of actinomycin D production byStreptomyces parvullus . We have attempted to discern whether this increase is due to a release from catabolite repression or to the synthesis of an inducer substance. The standard culture medium (glutamic acid-histidine-fructose medium) used in antibiotic production studies withS. parvullus containsl -glutamate as a major constituent.l -Glutamate is almost totally consumed before the onset of actinomycin D synthesis. The addition of 10 mMl -glutamate at this stage completely abolished actinomycin D production as well as tryptophan oxygenase synthesis. Fourteen amino acids were tested for a similar effect. Of these,l -glutamate andl -aspartate had the most dramatic effect on tryptophan oxygenase and β-galactosidase (β-d -galactosidase), another inducible enzyme. Standard glutamic acid-histidine-fructose medium, preincubated for 23 h to removel -glutamate, allowed the synthesis of actinomycin D and tryptophan oxygenase by cells at a stage of growth normally considered too early for antibiotic production. A chemically defined medium lackingl -glutamate and adjusted to pH 8.0 was designed to simulate the preincubation medium. The transfer of cells to this artificial preincubation medium resulted in the appearance of tryptophan oxygenase as early as 19 h before normal synthesis occurred, eliminating the possibility that an inducer molecule is synthesized and excreted during the preincubation period. The results of these studies suggest that the increase in tryptophan oxygenase activity before the onset of actinomycin D synthesis, as well as the synthesis of actinomycin D itself, is due to a release froml -glutamate catabolite repression.

Control of Actinomycin D Biosynthesis inStreptomyces parvullus: Regulation of Tryptophan Oxygenase Activity