The avermectins are a family of oleandrose disaccharide derivatives of pentacyclic lactones. Figure 4.1 presents a generalized structure of the avermectins produced by Streptomyces avermitilis. In addition, a number of key intermediates in the biosynthesis of the avermectins have been identified. These structures are as follows: aglycones lack the oleandrose disaccharide and possess a hydroxyl at C13; demethylavermectins lack one or more methoxyls on the oleandrose disaccharide and possess a hydroxyl at either or both the C3” and C3’; desfurano avermectins lack the oxygen at C8a and C6 and possess a CH3 at C8a and an H at C6; and 5-keto avermectins lack the hydroxyl (or methoxyl) at C5 and possess a keto group at C5.
KeywordsPropionate Carbon Avermectin Production Acetate Carbon Threonine Aldolase Average Specific Activity
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