... of the Escherichia coli protein SlyD with nickel ions illuminates the mechanism of regulation of its peptidyl-prolyl isomerase activity Luigi Martino1,2, Yangzi He1,*, Katherine L. D. Hands-Taylor1, ... PPIase site of SlyD. Although coher-ent with the fact that SlyD appears to interact in the proximity of the nickel ion high-affinity motif of HypB, the exact mechanism of the SlyD HypB interaction remains ... interactionsbetween the nickel ion and the protein is the keyfeature of the binding process.Further evidence that SlyD interacts with nickel ions with a 1 : 1 stoichiometry is provided by the analysis of the...