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Enzymatic Oxidation of beta-Apo-8'-carotenol to beta-Apo-14'-carotenal by an Enzyme Different from beta-Carotene-15,15'-dioxygenase

A. A. Dmitrovskii,1 N. N. Gessler,1,2 S. B. Gomboeva,1 Yu. V. Ershov,1 and V. Ya. Bykhovsky1

1Bakh Institute of Biochemistry, Russian Academy of Sciences, Leninskii pr. 33, Moscow, 117071 Russia; fax: (095) 954-27-32; E-mail: inbio@glas.aps.org

2To whom correspondence should be addressed.

Submitted March 5, 1997; revision submitted April 4, 1997.
Extracts of rat and rabbit intestinal mucosa were fractionated with ammonium sulfate. The precipitate contained beta-apocarotenoid-14',13'-dioxygenase (ADO) activity. beta-Apo-14'-carotenal was found to be the product of enzymatic cleavage of beta-apo-8'-carotenol. Activities of ADO and beta-carotene-15,15'-dioxygenase (CDO) were detected in the presence of thiols and were inactivated by 1,10-phenanthroline. Optimal pH values were 7.0 for ADO and 8.0 for CDO. Heating at 52°C inhibited ADO by 70% and produced no effect on CDO. ADO activity was maximal in the presence of sodium cholate or 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS). Sodium dodecylsulfate was required for maximal CDO activity. Proteins with ADO activity were not retained by phenyl-Sepharose CL-4B. CDO activity was eluted from columns only in the presence of detergents. The data suggest that the enzymes that catalyze the oxidative cleavage of beta-carotene to yield retinal are different from those that cleave beta-apo-8'-carotenol to yield beta-apo-14'-carotenal.
KEY WORDS: beta-carotene, retinal, beta-apo-8´-carotenol, beta-apo-14'-carotenal, beta-carotene-15,15'-dioxygenase, beta-apocarotenoid-14´,13'-dioxygenase, apocarotenoids, intestinal mucosa.