Cytochrome P450s constitute a big and important family of monooxygenase enzymes that play a key role in the metabolism.In the present study,it was found that CYP102A2 had higher activity to long-chain unsaturated fatty acids than to saturated acids.Notably,CYP102A2 had slight activity to lauraldehyde and tridecanal.Then all products were prepared and analyzed by GC-MS.For both aliphatic aldehydes,corresponding fatty acids and hydroxylated fatty acids at the position of ω-1,ω-2,or ω-3 were found,and about 70% of lauraldehyde (5.4mmol) and tridecanal (5mmol) were converted by CYP102A2 (17 U).Therefore,a catalytic pathway was proposed that lauraldehyde and tridecanal were firstly oxidized by CYP102A2 to lauric acid and tridecanoic acid,respectively,and then further oxidized to hydroxylated lauric acid and tridecanoic acid at the position of ω-1,ω-2,or ω-3.In addition,we found that CYP102A2 accelerated oxidizing nonanal,decanal and trans-2-decenoic acid to the corresponding acids.This is the first study that CYP102A2 catalyzed the oxidation of aldehydes.A new property for CYP102A2 to catalyze efficient oxidation of aliphatic aldehyde