RT Journal Article
SR Electronic
T1 Amino Acid Residues Affecting the Activities of Human Cytochrome P450 2C9 and 2C19
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 931
OP 936
DO 10.1124/dmd.30.8.931
VO 30
IS 8
A1 Toshiro Niwa
A1 Akira Kageyama
A1 Kae Kishimoto
A1 Yoshiyasu Yabusaki
A1 Fumihide Ishibashi
A1 Masanao Katagiri
YR 2002
UL http://dmd.aspetjournals.org/content/30/8/931.abstract
AB The amino acid residues affecting the substrate specificity of human cytochrome P450 CYP2C9 and CYP2C19 for their metabolic activities were investigated using chimeras and mutant enzymes, which were constructed by replacing the corresponding residues. Although CYP2C19 showed nearly the same tolbutamide hydroxylase activity as CYP2C9, the activities for the CYP2C19(H99I) mutant and the chimeras that replaced residues 1–212 were much lower than those for CYP2C19. The activities of the CYP2C19(H99I) mutant and the chimeras that replaced residues 228–340 were lower than those for CYP2C19 toward S-mephenytoin, aminopyrine, and testosterone. These results suggest that residues in substrate recognition site (SRS) 3 and 4 are important for the substrate specificity, whereas His99 is important in the substrate binding of CYP2C19. For the 4′-hydroxylation of diclofenac, CYP2C9 had a lowerKm and a higherVmax than CYP2C19. Although theVmax values for the CYP2C9(1–288)/CYP2C19(289–490) chimera and the CYP2C9(I99H, V292A, F295L, I331V) mutant were comparable to those for CYP2C9, itsKm value was comparable to that for CYP2C19. The Vmax andKm values for the CYP2C19(1–288)/CYP2C9(289–490) chimera were comparable to those for CYP2C19, and the activity by CYP2C9(1–230)/CYP2C19(231–490) chimera was negligible. These results suggest that the residues 292, 295, and/or 331 of CYP2C9 are essential for the recognition of substrate in CYP2C9 and that the residues of 231–288 including SRS 3 are important for the metabolizing capacity of CYP2C9. The American Society for Pharmacology and Experimental Therapeutics