Functional characterization of CYP2A13 polymorphisms

Xenobiotica. 2007 Dec;37(12):1439-49. doi: 10.1080/00498250701666265.


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 -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 -hydroxylation. CYP2A13 polymorphisms resulted in modest changes in coumarin 7-hydroxylation and NNK -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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence / genetics
  • Amino Acid Substitution
  • Aryl Hydrocarbon Hydroxylases / chemistry*
  • Aryl Hydrocarbon Hydroxylases / genetics*
  • Carcinogens / chemistry*
  • Carcinogens / metabolism
  • Coumarins / chemistry*
  • Coumarins / metabolism
  • Humans
  • Hydroxylation
  • Nitrosamines / chemistry*
  • Nitrosamines / metabolism
  • Polymorphism, Genetic*
  • Sequence Deletion


  • Carcinogens
  • Coumarins
  • Nitrosamines
  • 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone
  • coumarin
  • Aryl Hydrocarbon Hydroxylases
  • CYP2A13 protein, human
  • N'-nitrosonornicotine