BRUCINE AS A POTENT INDUCER OF CYP2B3, THE 3RD MEMBER OF THE CYP2B SUBFAMILY P450 IN RATS

We have indicated that strychnine and brucine induce concurrently an u nknown p450 (2B-UP) which cross-reacts with anti-CYP2B1 antibody (Fuji saki et al., J. Pharmacol. Exp. Ther., 268, 1024-1031, 1994). We purif ied ZB-UP from brucine-treated rats and characterized it in this study . The purification was achieved by solubilization with sodium cholate followed by successive chromatographic steps with omega-aminoctyl-Seph arose 4B, DEAE-Sephacel and hydroxyapatite. The minimum molecular weig ht of purified 2B-UP was calculated to be 48000 by sodium dodecyl sulf ate-gel electrophoresis. This preparation showed no Soret peak in the ultraviolet absorption spectrum indicating absence of heme. The amino terminal sequence of ZB-UP up to the 10th residue was consistent with the deduced amino acid sequence of CYP2B3 cDNA, but did not agree with the sequences of CYP2B1/2. The result strongly suggests that ZB-UP is CYP2B3. Thus, we indicated here that Strychnos alkaloid, brucine, is a potent inducer of the CYP2B3 or the closely related P450.