TY - JOUR
T1 - Functional characterization of CYP2A13 polymorphisms
AU - Schlicht, K. E.
AU - Michno, N.
AU - Smith, B. D.
AU - Scott, E. E.
AU - Murphy, Sharon E
PY - 2007/12
Y1 - 2007/12
N2 - CYP2A13 is an efficient catalyst of metabolic activation of the human carcinogens 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N′-nitrosonornicotine (NNN). This study investigated the functional consequences of CYP2A13 polymorphisms that result in single amino acid substitutions. Five CYP2A13 variants, namely CYP2A13*2 (R257C), CYP2A13*5 (F453Y), CYP2A13*6 (R494C), CYP2A13*8 (D158E), and CYP2A13*9 (V323L), were expressed and evaluated for coumarin binding affinity, coumarin 7-hydroxylation, and α-hydroxylation of (S)-NNN and NNK. In addition, the 133_134 Thr deletion variant, coded for by CYP2A13*3, was expressed but was not stable to the protein purification procedure. A 30-42% decrease in coumarin 7-hydroxylation catalytic efficiency was determined for R257C and D158E. No effect on coumarin binding or (S)-NNN metabolism was observed. Three variants, R257C, D158E, and V323L, had two- to threefold decreased catalytic efficiency for NNK α-hydroxylation. CYP2A13 polymorphisms resulted in modest changes in coumarin 7-hydroxylation and NNK α-hydroxylation activities in vitro. Although these changes are not likely to impact in vivo metabolism, these data should aid in the interpretation and design of future epidemiology studies.
AB - CYP2A13 is an efficient catalyst of metabolic activation of the human carcinogens 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N′-nitrosonornicotine (NNN). This study investigated the functional consequences of CYP2A13 polymorphisms that result in single amino acid substitutions. Five CYP2A13 variants, namely CYP2A13*2 (R257C), CYP2A13*5 (F453Y), CYP2A13*6 (R494C), CYP2A13*8 (D158E), and CYP2A13*9 (V323L), were expressed and evaluated for coumarin binding affinity, coumarin 7-hydroxylation, and α-hydroxylation of (S)-NNN and NNK. In addition, the 133_134 Thr deletion variant, coded for by CYP2A13*3, was expressed but was not stable to the protein purification procedure. A 30-42% decrease in coumarin 7-hydroxylation catalytic efficiency was determined for R257C and D158E. No effect on coumarin binding or (S)-NNN metabolism was observed. Three variants, R257C, D158E, and V323L, had two- to threefold decreased catalytic efficiency for NNK α-hydroxylation. CYP2A13 polymorphisms resulted in modest changes in coumarin 7-hydroxylation and NNK α-hydroxylation activities in vitro. Although these changes are not likely to impact in vivo metabolism, these data should aid in the interpretation and design of future epidemiology studies.
KW - 4-(methylnitrosamino)-1-(3-pyridyl)-1- butanone (NNK)
KW - CYP2A13
KW - Coumarin
KW - Cytochrome P450 (CYP)
KW - N′-nitrosonornicotine (NNN)
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U2 - 10.1080/00498250701666265
DO - 10.1080/00498250701666265
M3 - Article
C2 - 17922361
AN - SCOPUS:36348989610
SN - 0049-8254
VL - 37
SP - 1439
EP - 1449
JO - Xenobiotica
JF - Xenobiotica
IS - 12
ER -