Institut für Organische Chemie, Leibniz Universität Hannover, Schneiderberg 1 B, 30167 Hannover (Germany) http://uhw3dev.uni-hannover.de/oci/de/arbeitskreise/hahn/index.php.
Angew Chem Int Ed Engl. 2014 Dec 15;53(51):14240-4. doi: 10.1002/anie.201407979. Epub 2014 Oct 19.
Hydropyran rings are a common structural motif in reduced polyketides. Information on their biosynthetic formation and particularly the biochemical characterization of the responsible enzymes has only been reported in few cases. The dehydratase domain AmbDH3 from the ambruticin polyketide synthase was investigated. Through in vitro assay of the recombinant domain with synthetically-derived substrate surrogates, it was shown that it has a second catalytic activity as a cyclase that performs oxa-conjugate addition. Probing AmbDH3 with synthetic substrate analogues revealed stereoselectivity and substrate tolerance in both substeps. This is the first characterization of a pyran-forming cyclase from a cis-AT PKS system and the first report of a polyketide synthase domain with this kind of dual activity. Finally, it was revealed that this domain shows potential for application in chemoenzymatic synthesis.
氢吡喃环是还原聚酮化合物中常见的结构基序。关于其生物合成形成的信息，特别是负责的酶的生化特性，仅在少数情况下有报道。本文研究了来自安布鲁丁聚酮合酶的脱水酶结构域 AmbDH3。通过用合成衍生的底物类似物对重组结构域进行体外测定，表明它具有作为环化酶的第二种催化活性，可进行氧杂共轭加成。用合成的底物类似物探测 AmbDH3，在两个亚步骤中均显示出立体选择性和底物耐受性。这是首次对顺式 AT PKS 系统中的吡喃形成环化酶进行表征，也是首次报道具有这种双重活性的聚酮合酶结构域。最后，表明该结构域在化学酶合成中具有潜在的应用价值。
