Activation of L‐ornithine by cell‐free extracts of Bacillus brevis catalyzing the synthesis of gramicidin S

Purification of the Gramicidin S Synthesizing Activity in Bacillus brevis Extracts

“…The next stage, naturally, is the isolation of the individual enzymes and the elucidation of the mechanism of synthesis. Recently, fractionation of the gramicidin S synthesizing activity from an 11,000~g supernatant of B. brevis was briefly described [4]. The present report is a more detailed account of and also an extension of these experiments.…”

Amino acid dependent ATP—32PPi exchange measurement a filter paper disk method

“…A number of procedures have been described for the measurement of this activity [1][2][3][4]. They differ slightly in their experimental conditions, but all require the adsorption of the labelled ATP on activated charcoal after incubation in the presence of labelled PPi-The labelled ATP was then measured directly [1,2] on the charcoal or after elution with 1 N HCL [3] or by NH4OH [4] and measuring an aliquot of the solution in a liquid scintillation counter.…”

Oxygen-dependent inactivation of gramicidin S synthetase in Bacillus brevis

“…Gramicidin S (GS) synthetase is an enzyme complex responsible for the nonribosomal biosynthesis of GS in Bacillus brevis. The complex includes both a heavy (280,000 daltons) and a light (100,000 daltons) enzyme and catalyzes the formation of the cyclic decapeptide GS: 2 In the first step of GS biosynthesis, the individual amino acids are activated by ATP, which results in the formation of aminoacyl adenylates (7,12,21). The light enzyme catalyzes activation and racemization of L-to Dphenylalanine, and the heavy enzyme activates I Presnt address: George Washington University Law School, Washington, DC 20003. the other constituent amino acids (10).…”