SlyD is a putative folding helper protein from the Escherichia coli cytosol, which consists of an N-terminal prolyl isomerase domain of the FKBP type and a presumably unstructured C-terminal tail. It is involved in the biosynthesis of the metal cluster in the [NiFe]-hydrogenase enzymes, and exhibits several activities including that of a peptidyl-prolyl isomerase. Recombinant E. coli slyD was expressed in E. coli and purified by conventional chromatography. Alternative Names: WHP., FKBP-type peptidyl-prolyl cis-trans isomerase FKBP type peptidyl prolyl cis trans isomerase slyD protein, Histidine rich protein protein, FKBP-type peptidyl-prolyl cis-trans isomerase protein, Rotamase protein, PPIase protein, SlyD protein