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FEBS Lett. 2014 Aug 25;588(17):3117-22. doi: 10.1016/j.febslet.2014.06.050. Epub 2014 Jul 2.

Kinetic solvent isotope effect in steady-state turnover by CYP19A1 suggests involvement of Compound 1 for both hydroxylation and aromatization steps.

Author information

1
Department of Biochemistry, University of Illinois Urbana-Champaign, 505 S. Goodwin Avenue, Urbana, IL 61801, United States.
2
Department of Biochemistry, University of Illinois Urbana-Champaign, 505 S. Goodwin Avenue, Urbana, IL 61801, United States. Electronic address: s-sligar@illinois.edu.

Abstract

CYP19A1, or human aromatase catalyzes the conversion of androgens to estrogens in a three-step reaction through the formation of 19-hydroxy and 19-aldehyde intermediates. While the first two steps of hydroxylation are thought to proceed through a high-valent iron-oxo species, controversy exists surrounding the identity of the reaction intermediate that catalyzes the lyase and aromatization reaction. We investigated the kinetic isotope effect on the steady-state turnover of Nanodisc-incorporated human CYP19A1 to explore the mechanisms of this reaction. Our experiments reveal a significant (∼ 2.5) kinetic solvent isotope effect for the C10-C19 lyase reaction, similar to that of the first two hydroxylation steps (2.7 and 1.2). These data implicate the involvement of Compound 1 as a reactive intermediate in the final aromatization step of CYP19A1.

KEYWORDS:

CYP19A1; C–C lyase; Human aromatase; KSIE; Steady-state kinetics

PMID:
24997347
PMCID:
PMC4138292
DOI:
10.1016/j.febslet.2014.06.050
[Indexed for MEDLINE]
Free PMC Article

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