W3 PM Biomarkers
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in Ballroom 3

(MOS-1117-661406) Expression and characterization of channel catfish CYP 2X1.

MOSADEGHI, S.¹, FURNES, B.¹, SCHLENK, D.¹, ¹ UNIVERSITY OF CALIFORNIA, RIVERSIDE, RIVERSIDE, CA, USA

ABSTRACT- Previous purification and immunochemical studies in livers of channel catfish identified a novel cDNA encoding the cytochrome P450 isoform, CYP 2X1. The cDNA had an open reading frame of 1470 bp encoding a 490 amino acid protein, approximately 57 kD. To better characterize CYP 2X1, the protein was expressed in a baculovirous system. Isolated microsomes from Sf9 cells demonstrated a maximum CO reduced spectrum at 450nm, and exhibited a band at approximately 57 kD on SDS-PAGE. CYP 2X1 catalyzed aminopyrine and benzphetamine demethylase activity at 2.941 nmol/min/uM and 0.1910 nmol/min/uM respectively. However, enzymatic activity was not observed following incubation with p-nitrophenol, fenthion, benzylresorufin or pentoxyresorufin. These results indicate CYP 2X1 displays activities consistent with other piscine CYP 2 isoforms. Future studies will look at tissue distribution of CYP 2X1 in channel catfish.

Key words: cyp 2x1, channel catfish, expression, characterization