BELL PEPPER FRUIT FATTY-ACID HYDROPEROXIDE LYASE IS A CYTOCHROME-P450(CYP74B)

Fatty acid hydroperoxide lyases cleave a C-C bond adjacent to a hydrop eroxide group in lipoxygenase derived lipid hydroperoxides to form sho rt-chain aldehydes and ore-acids. Previously, we showed that fatty aci d hydroperoxide lyase from bell pepper fruits is a heme protein whose spectrophotometric properties greatly resemble a cytochrome P450, In o rder to ascertain the relationship of it to the P450 gene family, we h ave cloned cDNA encoding fatty acid hydroperoxide lyase from immature bell pepper fruits, The cDNA encodes 480 amino acids, and shares homol ogy with P450s mostly at the C terminus, The heme binding cysteine is recognizable at position 441, The most closely related P450 is allene oxide synthase (CYP74A), with which it has 40% identity, It qualifies the lyase as a member of a new P450 subfamily, CYP74B. From this findi ng, the enzyme is thought to be a novel member of P450 specialized for the metabolism of lipid peroxides.