title: Oxygen-dependent inactivation of gramicidin S synthetase in Bacillus brevis.
abstract: Incorporation of L-[14C]ornithine into gramicidin S by crude, unfractionated lysozyme extracts of Bacillus brevis ATCC 9999 was shown to represent the activity of the gramicidin synthetase complex. Frozen-thawed cells were the source of active extracts, but when cells were shaken in air at 37 degrees C, they rapidly lost activity in a first-order reaction with a half-life of 13 min. Protease inhibitors and inhibitors of energy metabolism had no effect on the inactivation process in frozen-thawed cells. Stabilization was achieved when the cells were shaken in nitrogen or helium instead of air. The addition of dithiothreitol produced a moderate degree of stabilization. The L-ornithine- and D-phenylalanine-activating activities of the gramicidin S synthetase complex were also lost during aeration of the cells. Crude cell-free extracts also lost activity when they were shaken in oxygen, but, in this case, inactivation was slower (half-life of 80 min). Nitrogen also stabilized these cell-free extracts.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000591:Amino Acid Isomerases / Q000378:metabolism*; D000596:Amino Acids / Q000494:pharmacology; D000693:Anaerobiosis; D000963:Antimetabolites / Q000494:pharmacology; D001407:Bacillus / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D001426:Bacterial Proteins / Q000378:metabolism; D002474:Cell-Free System; D003864:Depression, Chemical; D011756:Diphosphates / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D004347:Drug Interactions; D005615:Freezing; D006096:Gramicidin / Q000096:biosynthesis*; D009097:Multienzyme Complexes / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology*; D010453:Peptide Synthases / Q000378:metabolism*; D011480:Protease Inhibitors; D013997:Time Factors
chemical_list: D000596:Amino Acids; D000963:Antimetabolites; D001426:Bacterial Proteins; D011756:Diphosphates; D009097:Multienzyme Complexes; D011480:Protease Inhibitors; D006096:Gramicidin; D000255:Adenosine Triphosphate; D000591:Amino Acid Isomerases; D010453:Peptide Synthases; D010100:Oxygen; D004229:Dithiothreitol