Agroclavine 17hydroxylase

Kim et al. (1980) were seeking for enzymes specifically involved in the conversion of agroclavine into elymoclavine. In their study they characterised a specific cytochrome P-450 mono-oxygenase (non-inducible with liver enzyme inducers) catalysing exclusively the conversion of agroclavine to elymoclavine. The enzyme is located in the 15000-105000 g-fraction. NADPH and molecular oxygen were required for its activity. Under optimised condition 16% conversion was reached within one hour of incubation. The enzyme did not catalyse the conversion of DMAT to OH-DMAT that is apparently a non-specific reaction leading to elymoclavine catalysed by broad specificity oxygenases of Claviceps (Petroski and Kelleher, 1977; Saini and Anderson, 1978). Agroclavine hydroxylase activity was inhibited by carbon monoxide, but not by cyanide or EDTA that is typical for a cyctochrome P-450 monooxygenase. There is also a good correlation between alkaloid production and the enzyme activity. Practically comparable results concerning agroclavine hydroxylase (which they named agroclavine 17-mono-oxygenase) were obtained by Maier et al. (1988). They showed that agroclavine hydroxylase is inhibited by elymoclavine in a feed-back mechanism consistent with similar observation concerning feedback regulation of DMAT synthase and of other enzymatic conversions in the tetracyclic ergoline synthesis pathway (Cheng et al., 1980).

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