A homogeneous fluorescence anisotropy assay for measuring transglutaminase 2 activity

Transglutaminases catalyze the covalent linkage of protein polypeptides through their glutamine and lysine side chains. Tissue transglutaminase 2 (TG2) has been of particular interest given its potential role in several disorders, including a variety of cancers and neurodegenerative diseases. Here we report a biochemical assay that monitors TG2 activity by following an increase in the fluorescence anisotropy of a fluorescein-labeled substrate peptide as it conjugates to a bovine serum albumin (BSA) cosubstrate of larger hydrodynamic mass. The resulting homogeneous assay is sensitive to low TG2 concentrations (pM range) and is readily adapted to higher throughput formats. (C) 2013 Elsevier Inc. All rights reserved.