Nona- and deca-ketides

Bikaverin 3.89) is a rare example of a nonaketide. It is formed by simple folding of a single chain (see dotted line) [66]. 

Tetracyclines, e.g. 7-chlorotetracycline (3.100) are commercially important broad-spectrum antibiotics. Detailed information is available on the course of their biosynthesis as a result of an extensive study, using mutants in particular. This involved isolation of new products from differently blocked mutants and testing them as precursors in cross-feeding experiments. The structure (3.99) of mutant produced protetrone indicates the manner of folding in the polyketide as (3.97) (protetrone is a diversion from the main path- 

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