Structural Characterization of the Insulin-Degrading Enzyme by Microfluidic Modulation Spectroscopy

Valerie Ivancic, Eugene Ma, and Libo Wang, RedShiftBio
Noel D. Lazo, Clark University

Insulin-degrading enzyme (IDE) is a ubiquitously expressed Zn2+metalloprotease that digests several key substrates including insulin, glucagon, amyloid-b, and amylin. The structure of IDE under conditions of proteolysis is not known. Here, we used a new bioanalytical technique called Microfluidic Modulation Spectroscopy to directly probe the backbone structure of IDE in the absence and presence of ATP and insulin. In the presence of ATP, the backbone structure of IDE does not change. In contrast, the structure of IDE is altered in the presence of insulin such that the percentage of random coil is increased at the expense of b-sheet. Together, our results show that the interaction of ATP with IDE is localized to sidechains but the interaction of insulin with IDE leads to a perturbation in the backbone structure of the enzyme.