Human PAI-1with NBD labeled at the scissile bond of the reactive loop.  PAI-1 NBD-P1' was created by mutagenesis of the P1' serine residue (Ser347) at the P1-P1' scissile bond to cysteine. This provided a free thiol group for NBD labeling, a fluorescent probe highly sensitive to changes in dissolution and hydrophobic environment. The fluorescence emission of PAI-1 NBD-P1' is quenched upon cleavage of the reactive center loop by a target protease.

References
1. Olson S.T. et al. (2001) Biochemistry 40:11742-11756.