Functional characterization of CYP3A4.16: Catalytic activities toward midazolam and carbamazepine

K. Maekawa, T. Yoshimura, Y. Saito, Y. Fujimura, F. Aohara, C. Emoto, K. Iwasaki, N. Hanioka, S. Narimatsu, T. Niwa, J. Sawada

Research output: Contribution to journalArticle

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Abstract

1. To assess the substrate-dependent effects of the low-activity allele of human CYP3A4, CYP3A4*16 (Thr185Ser), a recombinant wild-type (CYP3A4.1) or variant (CYP3A4.16) protein was co-expressed with human NADPH-P450 reductase in Sf21 insect cells using a baculovirus-insect cell system. 2. The holo-CYP3A4 protein level of CYP3A4.16 in insect microsomes was slightly higher than that of CYP3A4.1, while no difference in total (apo- and holo-) CYP3A4 protein levels was observed between them. 3. When midazolam was used as a substrate, Km and Vmax for 1'-hydroxylation in CYP3A4.16 were significantly higher and lower, respectively, than those in the wild-type, resulting in a 50% decrease in intrinsic clearance (Vmax/Km) of the variant. In contrast, intrinsic clearance for 4-hydroxylation of the variant was decreased by 30% due to a significant increase in Km without a difference in Vmax. 4. Both the wild-type and variant exhibited sigmoidal kinetic profiles for carbamazepine 10,11-epoxide formation. When the modified two-site equation was applied for the analysis of kinetic parameters, Km2 and Vmax2 of CYP3A4.16 were approximately two times higher and lower than those of the wild-type, resulting in a 74% decrease in intrinsic clearance. 5. These results demonstrated that CYP3A4.16 shows the substrate-dependent altered kinetics compared with CYP3A4.1.

Original languageEnglish
Pages (from-to)140-147
Number of pages8
JournalXenobiotica
Volume39
Issue number2
DOIs
Publication statusPublished - Feb 2009

Fingerprint

Cytochrome P-450 CYP3A
Midazolam
Carbamazepine
Catalyst activity
Insects
Hydroxylation
Substrates
Sf9 Cells
NADPH-Ferrihemoprotein Reductase
Proteins
Kinetics
Baculoviridae
Microsomes
Kinetic parameters
Human Activities
Alleles

Keywords

  • CYP3A4
  • Function
  • Non-synonymous single nucleotide polymorphism (SNP)
  • Substrate dependency

ASJC Scopus subject areas

  • Pharmacology
  • Toxicology
  • Biochemistry
  • Health, Toxicology and Mutagenesis

Cite this

Maekawa, K., Yoshimura, T., Saito, Y., Fujimura, Y., Aohara, F., Emoto, C., ... Sawada, J. (2009). Functional characterization of CYP3A4.16: Catalytic activities toward midazolam and carbamazepine. Xenobiotica, 39(2), 140-147. https://doi.org/10.1080/00498250802617746

Functional characterization of CYP3A4.16 : Catalytic activities toward midazolam and carbamazepine. / Maekawa, K.; Yoshimura, T.; Saito, Y.; Fujimura, Y.; Aohara, F.; Emoto, C.; Iwasaki, K.; Hanioka, N.; Narimatsu, S.; Niwa, T.; Sawada, J.

In: Xenobiotica, Vol. 39, No. 2, 02.2009, p. 140-147.

Research output: Contribution to journalArticle

Maekawa, K, Yoshimura, T, Saito, Y, Fujimura, Y, Aohara, F, Emoto, C, Iwasaki, K, Hanioka, N, Narimatsu, S, Niwa, T & Sawada, J 2009, 'Functional characterization of CYP3A4.16: Catalytic activities toward midazolam and carbamazepine', Xenobiotica, vol. 39, no. 2, pp. 140-147. https://doi.org/10.1080/00498250802617746
Maekawa, K. ; Yoshimura, T. ; Saito, Y. ; Fujimura, Y. ; Aohara, F. ; Emoto, C. ; Iwasaki, K. ; Hanioka, N. ; Narimatsu, S. ; Niwa, T. ; Sawada, J. / Functional characterization of CYP3A4.16 : Catalytic activities toward midazolam and carbamazepine. In: Xenobiotica. 2009 ; Vol. 39, No. 2. pp. 140-147.
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