149-31-5Relevant articles and documents
Substrate-dependent stereospecificity of Tyl-KR1: An isolated polyketide synthase ketoreductase domain from Streptomyces fradiae
H?ckh, Matthias,Müller, Michael,Lüdeke, Steffen
, p. 8922 - 8928 (2013)
The stereospecificity of an enzymatic reaction depends on the way in which a substrate and its enantiomer bind to the active site. These binding modes cannot be easily predicted. We have studied the stereospecificity and stereoselectivity of the ketoreductase domain Tyl-KR1 of the tylactone polyketide synthase from Streptomyces fradiae by analysing the stereochemical outcome of the reduction of five different keto ester substrates. The absolute configuration of the Tyl-KR1 reduction products was determined by using vibrational circular dichroism (VCD) spectroscopy combined with quantum chemical calculations. The conversion of only one of the tested substrates, 2-methyl-3-oxovaleric acid N-acetylcysteamine thioester, afforded the expected anti-(2R,3R) configuration of the α-methyl-β-hydroxyl ester product, representing the stereochemistry observed for the physiological polyketide product tylactone. For all other substrates, which were modified with respect to the type of ester and/or the chain length (C4 instead of C 5), the opposite configuration (anti-(2S,3S)) was obtained with significant enantio- and diastereoselectivity. Inversion of both stereocentres suggests completely different binding modes invoked by only minor modifications of the substrate structure. Substrate dependence: The stereospecificity of an enzymatic reduction depends on the way a substrate binds to the active site. By using vibrational circular dichroism, it was shown that the stereospecificity and stereoselectivity of the ketoreductase Tyl-KR1 from a polyketide synthase complex in Streptomyces fradiae are inverted for different surrogates of polyketide-like substrates (see figure). Copyright
Asymmetric cross- and self-aldol reactions of aldehydes in water with a polystyrene-supported triazolylproline organocatalyst
Llanes, Patricia,Sayalero, Sonia,Rodríguez-Escrich, Carles,Pericàs, Miquel A.
supporting information, p. 3507 - 3512 (2016/07/06)
A polystyrene (PS) immobilized triazolylproline has been prepared by a bottom-up approach involving co-polymerization with full regiocontrol. The resulting PS resin swells in water and has been applied to the enantioselective cross-aldol reaction and to the self-aldol reaction of aldehydes under essentially neat conditions, excellent yields and stereoselectivities being recorded.
Erratum: Toward an artificial aldolase (Organic Letters (2008) 10 (337-340))
Font, Daniel,Sayalero, Sonia,Bastero, Amaia,Jimeno, Ciril,Pericas, Miquel A.
supporting information; experimental part, p. 2678 - 2678 (2010/08/22)
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