A cold active transglutaminase from Antarctic krill (Euphausia superba): Purification, characterization and application in the modification of cold-set gelatin gel

•A 78 kDa transglutaminase was purified from cold-adapted Antarctic krill.•The transglutaminase was optimally active at 0-10 °C but lost ∼50% above 45 °C.•Calcium and sodium ions enhanced the transglutaminase activity.•The transglutaminase improved properties of gelatin gel prepared at 4 °C.

Transglutaminase (TGase), EC 2.3.2.13, was purified from whole Antarctic krill (Euphausia superba) using ammonium sulfate fractionation and DEAE-Sephacel chromatography. The purified enzyme had specific activity, purification fold and yield of 53.518 U/mg, 10.272 and 10.992%, respectively. The molecular weight of the purified Antarctic krill TGase was estimated to be 78 kDa using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimal pH and temperature for the activity of the purified TGase were pH 8.0-9.0 and 0-10 °C, respectively. However, the TGase activity reduced to 50% at a higher temperature of 45 °C. The cations Ca++ and Na+ activated the purified TGase activity optimally at levels of incorporation of 10 mM and 1.8 mM, respectively. Addition of TGase at 0.1 U/mg increased the gel strength (p < 0.05), setting temperature, setting time (p < 0.05) and melting temperature (p < 0.05) of cold-set gelatin gel.