Cloning and expression of beta,beta-carotene 15,15 '-dioxygenase

beta,beta-Carotene 15,15'-dioxygenase cleaves beta-carotene into two molecu les of retinal and is therefore the key enzyme in beta-carotene metabolism to vitamin A. In the present study, it was possible to enrich the chicken b eta,beta-carotene 15,15'-dioxygenase to such an extent that partial amino a cid sequence information could be obtained to design degenerate oligonucleo tides. With RT-PCR a cDNA fragment could be obtained and used subsequently in a radioactive screening of a chicken duodenal expression library. We clo ned the first eukaryotic beta,beta-carotene 15,15'-dioxygenase which symmet rically cleaves beta-carotene at the 15,15'-double bond. (C) 2000 Academic Press.