Purification of transglutaminase from scallop striated adductor muscle andNaCl-induced inactivation

Tissue type transglutaminase (TGase) was purified from scallop striated add uctor muscle with successive chromatographies of DE-52 cellulose, Sephacryl S-300, and Mono Q columns. The yield and purification of the enzymatic act ivity was 16.6% and 101.9-fold, respectively. The molecular mass of purifie d enzyme was estimated to be 95 kDa by sodium dodecylsulfate-polyacrylamide gel electrophoresis analysis. Scallop TGase was Ca2+-dependent and strongl y inactivated by rho -chloromercuribenzoic acid, N-ethylmaleimide, Cu2+, an d Zn2+, meaning it belongs to the thiol group of enzymes as well as being a mammalian enzyme. When scallop TGase was incubated in 0.5 M NaCl without s ubstrate for 2 h at 20 degreesC and pH 7.5, enzymatic activity decreased to 14.4% of its original. However, a conformational change in the TGase molec ule was not detected by either fluorescent, ultraviolet, and circular dichr oism spectra analyses compared to the enzyme incubated without NaCl. in add ition, the enzyme inactivated by NaCl was partially recovered by the diluti on of salt concentration, which means that the NaCl-induced inactivation pr ocess is reversible to some extent. These results suggest that NaCl-induced modulation of the TGase molecule occurs via a small conformational change.