Poly oxygenase

Braaz R, P Fischer, D Jendrossek (2004) Novel type of heme-dependent oxygenase catalyzes oxidative cleavage of rubber (poly-cw-l,4-isoprene). Appl Environ Microbiol 70 7388-7395. 

An extracellular enzyme from Xanthomonas sp. is able to degrade poly(c -l,4-isoprene) with the production of 12-keto-4,8-dimethyltrideca-4,8-diene-l-al (Braaz et al. 2004), and functions as a heme-dependent oxygenase (Braaz et al. 2005). 

Braaz R, W Armbruster, D Jendrossek (2005) Heme-dependent rubber oxygenase Roxa of Xanthomonas sp. cleaves the carbon backbone of poly(cw-l,4-isoprene) by a dioxygenase mechanism. Appl Environ Microbiol 71 2473-2478. 

Using these techniques (combinatorial biosynthesis) with streptomycetes, the polyketides have now been investigated, including not only the macrolides (e. g., erythromycin) but also polycyclic aromatic compounds (e.g., actinorhodin, tetracenomycins). The formation of hybrids can alter not only the size of the poly ketide skeleton, its stereochemistry or its functionality but also enzyme systems of the later steps of biosynthesis such as, e. g., oxygenases or glycosy Itrans-ferases. In practice major difficulties arise because each intermediate in the biosynthetic sequence is a substrate for the following enzyme thus if a changed substrate is not accepted by the respective enzyme the biosynthesis breaks down. 

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