title: Effect of bongkrekic acid, a product of Pseudomonas cocovenenans, on thiol proteases.
abstract: The in vitro effect of bongkrekic acid on stem bromelain, papain and ficin was studied. The hydrolysis of casein by these enzymes was inhibited by bongkrekic acid, but the inhibition was always incomplete even with a large excess of the effector. Using a fully activated specimen of stem bromelain, purified on an organomercurial agarose affinity column, the inhibition by bongkrekic acid was not stoichiometric. The SH group of cysteine remained intact after incubation with an excess of bongkrekic acid at 24 degrees C for 20 min. However, partial inhibition of stem bromelain by bongkrekic acid was reversed by incubation at 37 degrees C for 5 min with 5mM cysteine or 2-mercaptoethanol. Ethylene glycol and glycerol had no such restorative effect. These results indicate that molecules of bongkrekic acid are non-covalently bound to a thiol protease, only partially and reversibly shielding its essential SH group.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001427:Bacterial Toxins / Q000494:pharmacology*; D001865:Bongkrekic Acid / Q000494:pharmacology*; D001963:Bromelains / Q000032:analysis / Q000037:antagonists & inhibitors; D011480:Protease Inhibitors; D011549:Pseudomonas / Q000472:pathogenicity*
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D011480:Protease Inhibitors; D001865:Bongkrekic Acid; D001963:Bromelains