4KQX:
reference: General approach to reversing ketol-acid reductoisomerase cofactor dependence from NADPH to NADH., Brinkmann-Chen S, Flock T, Cahn JK, Snow CD, Brustad EM, McIntosh JA, Meinhold P, Zhang L, Arnold FH, Proc Natl Acad Sci U S A. 2013 Jul 2;110(27):10946-51. doi:, 10.1073/pnas.1306073110. Epub 2013 Jun 17. PMID: 23776225

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