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.

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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.

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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.

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