Purification and properties of P-450lm3b, a constitutive form of cytochrome P-450, from rabbit liver microsomes

Dennis Koop, Minor J. Coon

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

This laboratory has previously reported the occurrence in rabbit liver microsomes of a non-inducible form of cytochrome P-450, designated P-450lm3b because of its electrophoretic mobility relative to that of phenobarbital-inducible P-450lm2 and 5,6-benzoflavone-inducible P-450lm4. In the present study, P-450lm3b was purified to electrophoretic homogeneity and a specific content of over 19 nmol per mg of protein by chromatographic procedures carried out in the presence of detergents. The isolated cytochrome has a minimal molecular weight of 52,000 and exhibits absorption maxima at 418, 537, and 571 nm in the oxidized state, 412 and 547 nm in the reduced state, and 451 and 555 nm as the CO complex. In a reconstituted system containing NADPH-cytochrome P-450 reductase and phosphatidylcholine, P-450lm3b has relatively high activity in the hydroxylation of testosterone in the 6β and 16α positions as well as significant activity toward a number of other substrates tested. The NADPH oxidase activity of P-450lm3b is less than half that of P-450lm2 and lm4.

Original languageEnglish (US)
Pages (from-to)1075-1081
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume91
Issue number3
DOIs
StatePublished - Dec 14 1979
Externally publishedYes

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beta-Naphthoflavone
NADPH-Ferrihemoprotein Reductase
Electrophoretic mobility
Hydroxylation
NADPH Oxidase
Liver Microsomes
Carbon Monoxide
Cytochromes
Phenobarbital
Phosphatidylcholines
Detergents
Liver
Cytochrome P-450 Enzyme System
Purification
Testosterone
Molecular Weight
Molecular weight
Rabbits
Substrates
Proteins

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Cite this

Purification and properties of P-450lm3b, a constitutive form of cytochrome P-450, from rabbit liver microsomes. / Koop, Dennis; Coon, Minor J.

In: Biochemical and Biophysical Research Communications, Vol. 91, No. 3, 14.12.1979, p. 1075-1081.

Research output: Contribution to journalArticle

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N2 - This laboratory has previously reported the occurrence in rabbit liver microsomes of a non-inducible form of cytochrome P-450, designated P-450lm3b because of its electrophoretic mobility relative to that of phenobarbital-inducible P-450lm2 and 5,6-benzoflavone-inducible P-450lm4. In the present study, P-450lm3b was purified to electrophoretic homogeneity and a specific content of over 19 nmol per mg of protein by chromatographic procedures carried out in the presence of detergents. The isolated cytochrome has a minimal molecular weight of 52,000 and exhibits absorption maxima at 418, 537, and 571 nm in the oxidized state, 412 and 547 nm in the reduced state, and 451 and 555 nm as the CO complex. In a reconstituted system containing NADPH-cytochrome P-450 reductase and phosphatidylcholine, P-450lm3b has relatively high activity in the hydroxylation of testosterone in the 6β and 16α positions as well as significant activity toward a number of other substrates tested. The NADPH oxidase activity of P-450lm3b is less than half that of P-450lm2 and lm4.

AB - This laboratory has previously reported the occurrence in rabbit liver microsomes of a non-inducible form of cytochrome P-450, designated P-450lm3b because of its electrophoretic mobility relative to that of phenobarbital-inducible P-450lm2 and 5,6-benzoflavone-inducible P-450lm4. In the present study, P-450lm3b was purified to electrophoretic homogeneity and a specific content of over 19 nmol per mg of protein by chromatographic procedures carried out in the presence of detergents. The isolated cytochrome has a minimal molecular weight of 52,000 and exhibits absorption maxima at 418, 537, and 571 nm in the oxidized state, 412 and 547 nm in the reduced state, and 451 and 555 nm as the CO complex. In a reconstituted system containing NADPH-cytochrome P-450 reductase and phosphatidylcholine, P-450lm3b has relatively high activity in the hydroxylation of testosterone in the 6β and 16α positions as well as significant activity toward a number of other substrates tested. The NADPH oxidase activity of P-450lm3b is less than half that of P-450lm2 and lm4.

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