4L4X:
reference: Structural Studies of an A2-Type Modular Polyketide Synthase Ketoreductase Reveal Features Controlling alpha-Substituent Stereochemistry., Zheng J, Piasecki SK, Keatinge-Clay AT, ACS Chem Biol. 2013 Sep 20;8(9):1964-71. doi: 10.1021/cb400161g. Epub 2013 Jun, 24. PMID: 23755878

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