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J Biol Chem

Title:		Identification and characterization of a mammalian enzyme catalyzing the asymmetric oxidative cleavage of provitamin A
Author(s):		Kiefer C; Hessel S; Lampert JM; Vogt K; Lederer MO; Breithaupt DE; von Lintig J;
Address:		"University of Freiburg, Instiute of Biology I, Animal Physiology and Neurobiology, Hauptstrasse 1, D-79104 Freiburg, Germany"
Journal Title:		J Biol Chem
Year:		2001
Volume:		20010129
Issue:		17
Page Number:		14110 - 14116
DOI:		10.1074/jbc.M011510200
ISSN/ISBN:		0021-9258 (Print) 0021-9258 (Linking)
Abstract:		"In vertebrates, symmetric versus asymmetric cleavage of beta-carotene in the biosynthesis of vitamin A and its derivatives has been controversially discussed. Recently we have been able to identify a cDNA encoding a metazoan beta,beta-carotene-15,15'-dioxygenase from the fruit fly Drosophila melanogaster. This enzyme catalyzes the key step in vitamin A biosynthesis, symmetrically cleaving beta-carotene to give two molecules of retinal. Mutations in the corresponding gene are known to lead to a blind, vitamin A-deficient phenotype. Orthologs of this enzyme have very recently been found also in vertebrates and molecularly characterized. Here we report the identification of a cDNA from mouse encoding a second type of carotene dioxygenase catalyzing exclusively the asymmetric oxidative cleavage of beta-carotene at the 9',10' double bond of beta-carotene and resulting in the formation of beta-apo-10'-carotenal and beta-ionone, a substance known as a floral scent from roses, for example. Besides beta-carotene, lycopene is also oxidatively cleaved by the enzyme. The deduced amino acid sequence shares significant sequence identity with the beta,beta-carotene-15,15'-dioxygenases, and the two enzyme types have several conserved motifs. To establish its occurrence in different vertebrates, we then attempted and succeeded in cloning cDNAs encoding this new type of carotene dioxygenase from human and zebrafish as well. As regards their possible role, the apocarotenals formed by this enzyme may be the precursors for the biosynthesis of retinoic acid or exert unknown physiological effects. Thus, in contrast to Drosophila, in vertebrates both symmetric and asymmetric cleavage pathways exist for carotenes, revealing a greater complexity of carotene metabolism"
Keywords:		"Amino Acid Sequence Animals Carotenoids/chemistry/metabolism Catalysis Chromatography, High Pressure Liquid Cloning, Molecular DNA, Complementary/metabolism Drosophila/enzymology Drosophila Proteins Expressed Sequence Tags Female Gene Library Humans Lycop;"
Notes:		"MedlineKiefer, C Hessel, S Lampert, J M Vogt, K Lederer, M O Breithaupt, D E von Lintig, J eng 2001/03/30 J Biol Chem. 2001 Apr 27; 276(17):14110-6. doi: 10.1074/jbc.M011510200. Epub 2001 Jan 29"