A heme-thiolate protein (P-450). The conversion of substrate into product involves the hydroxylation of the syn-methyl (C9), intramolecular cyclization to the hemiketal and dehydration to the furan . This is the second cytochrome P-450-mediated step of monoterpene metabolism in peppermint, with the other step being catalysed by EC 126.96.36.199, (S)-limonene 3-monooxygenase .
Bertea, C.M., Schalk, M., Karp, F., Maffei, M. and Croteau, R. Demonstration that menthofuran synthase of mint (Mentha) is a cytochrome P450 monooxygenase: cloning, functional expression, and characterization of the responsible gene. Arch. Biochem. Biophys.390 (2001) 279–286. [DOI] [PMID: 11396930]
Mahmoud, S.S. and Croteau, R.B. Menthofuran regulates essential oil biosynthesis in peppermint by controlling a downstream monoterpene reductase. Proc. Natl. Acad. Sci. USA100 (2003) 14481–14486. [DOI] [PMID: 14623962]