Theoretical calculation of triazolam hydroxylation and endogenous steroid inhibition in the active site of CYP3A4

Nao Torimoto, Itsuko Ishii, Masayuki Hata, Yukari Kobayashi, Hiroyoshi Nakamura, Noritaka Ariyoshi, Mitsukazu Kitada

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

CYP3A4 has unusual kinetic characteristics because it has a large active site. CYP3A4 produced more 4-hydroxytriazolam than α-hydroxytriazolam at concentrations of more than 60 μM triazolam, and different steroids had different inhibitory effects on the system. To clarify these interesting observations, the interactions between substrate and substrate/steroid were investigated by theoretical calculations. When two triazolam molecules were docked into the active site, the distance between the O-atom and the 4-hydroxylated site was less than the distance to the α-hydroxylated site because of interaction between the two triazolam molecules. Estradiol inhibited both α- and 4-hydroxytriazolam formation by 50%. Dehydroepiandrosterone (DHEA) inhibited α-hydroxylation more than 4-hydroxytriazolam formation, whereas aldosterone had no effect. When one triazolam molecule and one steroid molecule were simultaneously docked, estradiol increased the distance between the O-atom and the two hydroxylated sites, DHEA only increased the distance between the O-atom and α-hydroxylated site, and aldosterone did not change the distances. The relevant angles of Fe-O-C in the hydroxylated site of triazolam also widened, together with increased distance. These findings indicate that formation of a substrate and substrate/effector complex in the active site may be a factor for determining the enzyme kinetic parameters of CYP3A4.

Original languageEnglish
Pages (from-to)223-232
Number of pages10
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Volume1774
Issue number2
DOIs
Publication statusPublished - Feb 2007
Externally publishedYes

Fingerprint

Triazolam
Cytochrome P-450 CYP3A
Hydroxylation
Catalytic Domain
Steroids
Molecules
Dehydroepiandrosterone
Substrates
Aldosterone
Atoms
Estradiol
Enzyme kinetics
Kinetic parameters
Enzymes
4-hydroxytriazolam

Keywords

  • CYP3A4
  • Endogenous steroid
  • Theoretical calculation
  • Triazolam

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Genetics

Cite this

Theoretical calculation of triazolam hydroxylation and endogenous steroid inhibition in the active site of CYP3A4. / Torimoto, Nao; Ishii, Itsuko; Hata, Masayuki; Kobayashi, Yukari; Nakamura, Hiroyoshi; Ariyoshi, Noritaka; Kitada, Mitsukazu.

In: Biochimica et Biophysica Acta - Proteins and Proteomics, Vol. 1774, No. 2, 02.2007, p. 223-232.

Research output: Contribution to journalArticle

Torimoto, Nao ; Ishii, Itsuko ; Hata, Masayuki ; Kobayashi, Yukari ; Nakamura, Hiroyoshi ; Ariyoshi, Noritaka ; Kitada, Mitsukazu. / Theoretical calculation of triazolam hydroxylation and endogenous steroid inhibition in the active site of CYP3A4. In: Biochimica et Biophysica Acta - Proteins and Proteomics. 2007 ; Vol. 1774, No. 2. pp. 223-232.
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