Peptidyl-prolyl isomerase (PPIase) Pin1 catalyzes cis/trans isomerization of the phospho-Serine/Threonine-Proline peptide bonds (1-5). Pin1 consists of short N-terminal protein-protein interaction domain that allows enzyme to bind phosphoproteins and longer C-terminal izomerase domain (1-5).Pin1 has many biological substrates, plays critical role in cell-cycle regulation, and up-regulated in many human cancers (1-5). Recently, Pin1 was linked to the Alzheimer’s disease pathogenesis (1, 2, 4). Pin1 can bind phosphorylated Thr-212/231 residues of Tau protein and increase its deposphorylation that may prevent formation of Tau neurofibrilary tangles (1, 2, 4). The SensoLyte® Green Pin1 Assay Kit uses a fluorogenic substrate in the cis isoform. Pin1 changes substrate into trans conformation, which is then readily cleaved to generate fluorescent signal which can be monitored at Ex/Em=490/520nm. Increase in fluorescence intensity is directly proportional to the Pin1 activity.

Figure. (A). SensoLyte® Green Pin1 Activity example (uncatalyzed corresponds to the Pin1 developer only reaction). (B). Tannic acid inhibition of Pin1 activity measured with SensoLyte® Green Pin1 Activity Assay Kit.