Purification and characterization of a tissue-type transglutaminase from red sea bream (Pagrus major).

A tissue-type transglutaminase (TGase) was purified from liver tissue of the red sea bream, Pagrus major, by ion-exchange chromatography and heparin-Sepharose affinity chromatography. Its activity was assessed using a fluorometric assay to measure the incorporation of monodansylcadaverine into N,N'-dimethyl casein. The molecular mass of purified TGase was estimated to be 78 kDa by SDS-polyacrylamide gel electrophoresis. The enzyme required Ca2+ to express its activity, although 10 mM Sr2+ also activated the enzyme fully. TGase activity was maximal at pH 9.0-9.5, and the enzyme was strongly inhibited by sulfhydryl reagents. The purified enzyme catalyzed the cross-linking of myosin heavy chain obtained from Alaska pollack, resulting in gelation of an actomyosin solution. The partial amino acid sequence of this fish TGase showed divisionally significant similarity to TGase from guinea pig liver.