Liver microsomal cytochromes P-450 and azoreductase activity

J Biol Chem. 1978 Jul 10;253(13):4512-3.


Hepatic microsomal azoreductase activity with amaranth (3-hydroxy-4[(4-sulfo-1-naphthalenyl)azo]-2,7-naphthalenedisulfonic acid trisodium salt) as a substrate is proportional to the levels of microsomal cytochrome P-450 from control or phenobarbital-pretreated rats and mice or cytochrome P-448 from 3-methylchol-anthrene-pretreated animals. In the "inducible" C57B/6J strain of mice, 3-methylcholanthrene and phenobarbital pretreatment cause an increase in cytochrome P-448 and P-450 levels, respectively, which is directly proportional to the increase of azoreductase activity. However, in the "noninducible" DBA/2J strain of mice, only phenobarbital treatment causes the increase both in cytochrome P-450 levels and azoreductase activity, while 3-methylcholanthrene has no effect. These experiments suggest that the P-450 type cytochromes are responsible for azoreductase activity in liver microsomes.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amaranth Dye / metabolism
  • Animals
  • Azo Compounds / metabolism*
  • Cytochrome P-450 Enzyme System / metabolism*
  • Cytochromes / metabolism
  • Enzyme Induction
  • Methylcholanthrene / pharmacology
  • Mice
  • Microsomes, Liver / enzymology*
  • Mixed Function Oxygenases / metabolism
  • NADH, NADPH Oxidoreductases / metabolism*
  • Phenobarbital / pharmacology
  • Rats
  • p-Dimethylaminoazobenzene


  • Azo Compounds
  • Cytochromes
  • Methylcholanthrene
  • Cytochrome P-450 Enzyme System
  • Amaranth Dye
  • p-Dimethylaminoazobenzene
  • Mixed Function Oxygenases
  • NADH, NADPH Oxidoreductases
  • Phenobarbital