Purification of the Gramicidin S Synthesizing Activity in <em>Bacillus brevis</em> Extracts.

A 20 fold purification of the gramicidin S synthesizing activity in a 11,000 &#215; g supernatant from Bacillus brevis has been achieved. The purification procedure involves precipitation of undesired material with streptomycin sulphate, followed by precipitation of gramicidin S synthesizing activity at 40% (NH4)2SO4 saturation and fractionation on DEAE-Sephadex. All gramicidin S synthesizing activity appeared in one peak. It incorporated labelled phenylalanine, proline, valine, ornithine and tcucine to the same extent into gramicidin S. The gramicidin S synthesizing activity was found to be stable in a 0.05 M potassium phosphate buffer (pH 7.1) containing glutathione (0.01 M) and glycerol (20%, v/v) for at least 3 days at + 4&#176; and four weeks at -20&#176;. [ABSTRACT FROM AUTHOR]