The guanidinium chloride- and urea-induced unfolding of FprA, a mycobacterium NADPH-ferredoxin reductase, was examined in detail using multiple spectroscopic techniques, enzyme activity measurements and size exclusion chromatography. The equilibrium unfolding of FprA by urea is a cooperative process where no stabilization of any partially folded inter-mediate of protein is observed. In comparison, the unfolding of FprA by guanidinium chloride proceeds through intermediates that are stabilized by interaction of protein with guanidinium chloride. .
