Departamento de Bioquı´mica y Biologı´a Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Spain; Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA Reduction potential determinations of K75E, E139K and E301A ferredoxin-NADP+ reductases provide valuable information concerning the factors that contribute to tune the flavin reduction potential. Thus, while E139 is not involved in such modulation, the K75 side-chain tunes the flavin potential by creating a defined environment that modulates the FAD conformation. .
