IMMUNOLOGICAL AND BIOCHEMICAL-CHARACTERIZATION OF CYTOCHROMES P-450 IN MULLET

Immunoblots (Western blot) of mullet liver microsomes revealed the presence of multiple forms of P-450 that appear to be structurally related to rainbow trout CYP1A1 and CYP2K1 and to P-450 LMC1 and LMC4, but not to LMC5. 3-Methylchoanthrene but not beta-naphthoflavone induced a major 58 kDa liver protein and a minor 56 kDa protein in mullet that both cross-reacted with anti-trout CYP1A1 IgG. The levels of immunodetectable P-450s and the activities of microsomal lauric acid hydroxylase, DMBA hydroxylase and progesterone 6 beta-hydroxylase were several times lower in mullet liver than in rainbow trout liver; however, progesterone 16 alpha-hydroxylase and progesterone 20 alpha-hydroxylase activities were 4-fold and 6-fold higher, respectively, in mullet than in trout liver.