Purification and characterization of human liver cytochrome P-450-ALC.
Cytochrome P-450-ALC, an ethanol-oxidizing form of microsomal cytochrome P-450 (P-450), has been purified from human liver. P-450-ALC (Mr = 54,000 daltons) is a low-spin ferric hemeprotein with a CO-reduced Soret maximum at 452 nm, and has an NH2-terminal amino acid sequence nearly identical to that deduced from a human P-450-ALC cDNA clone. In a reconstituted system, P-450-ALC oxidizes ethanol and aniline at turnover rates (12.2 and 7.3 nmol min-1, respectively) 10-fold greater than two other human P-450 isozymes (termed P-450-B and P-450-C) purified from the same liver. Both P-450-ALC and P-450-C effectively demethylate N-nitrosodimethylamine (NDMA) at low substrate concentrations (0.5 mM), especially in the presence of cytochrome b5. Our results provide direct evidence for a liver P-450 isozyme in humans with catalytic properties similar to the related alcohol-inducible rodent P-450s and also reveal a new human NDMA demethylase.
Lasker
J M
JM
Alcohol Research and Treatment Center, Bronx Veterans Administration Medical Center, NY.
Raucy
J
J
Kubota
S
S
Bloswick
B P
BP
Black
M
M
Lieber
C S
CS
D000595:Amino Acid Sequence; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D006801:Humans; D008862:Microsomes, Liver / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012689:Sequence Homology, Nucleic Acid; D013379:Substrate Specificity
D000431:Ethanol; D003577:Cytochrome P-450 Enzyme System