Physical Sciences and Mathematics Commons^™

Determining Protease Substrate Selectivity And Inhibition By Label-Free Supramolecular Tandem Enzyme Assays, Garima Ghale, Vijayakumar Ramalingam, Adam R. Urbach, Werner M. Nau

Chemistry Faculty Research

An analytical method has been developed for the continuous monitoring of protease activity on unlabeled peptides in real time by fluorescence spectroscopy. The assay is enabled by a reporter pair comprising the macrocycle cucurbit[7]uril (CB7) and the fluorescent dye acridine orange (AO). CB7 functions by selectively recognizing N-terminal phenylalanine residues as they are produced during the enzymatic cleavage of enkephalin-type peptides by the metalloendopeptidase thermolysin. The substrate peptides (e.g., Thr-Gly-Ala-Phe-Met-NH₂) bind to CB7 with moderately high affinity (K ≈ 10⁴ M^–1), while their cleavage products (e.g., Phe-Met-NH₂) bind very tightly (K …