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 language | English |
|---|---|
| Pages (from-to) | 223-232 |
| Number of pages | 10 |
| Journal | Biochimica et Biophysica Acta - Proteins and Proteomics |
| Volume | 1774 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Feb 2007 |
| Externally published | Yes |
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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 journal › Article
}
TY - JOUR
T1 - Theoretical calculation of triazolam hydroxylation and endogenous steroid inhibition in the active site of CYP3A4
AU - Torimoto, Nao
AU - Ishii, Itsuko
AU - Hata, Masayuki
AU - Kobayashi, Yukari
AU - Nakamura, Hiroyoshi
AU - Ariyoshi, Noritaka
AU - Kitada, Mitsukazu
PY - 2007/2
Y1 - 2007/2
N2 - 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.
AB - 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.
KW - CYP3A4
KW - Endogenous steroid
KW - Theoretical calculation
KW - Triazolam
UR - http://www.scopus.com/inward/record.url?scp=33846842087&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33846842087&partnerID=8YFLogxK
U2 - 10.1016/j.bbapap.2006.11.009
DO - 10.1016/j.bbapap.2006.11.009
M3 - Article
VL - 1774
SP - 223
EP - 232
JO - Biochimica et Biophysica Acta - Proteins and Proteomics
JF - Biochimica et Biophysica Acta - Proteins and Proteomics
SN - 1570-9639
IS - 2
ER -