A novel fibrinolytic serine metalloprotease from the marine Serratia marcescens subsp sakuensis: Purification and characterization

This study demonstrates the purification and characterization of a fibrinolytic serine metalloprotease from the marine Serratia marcescens subsp. sakuensis (KU296189.1). The purified enzyme (1033 U/mg) had a molecular weight of 43 KDa, with optimum pH and temperature being 7 and 55 degrees C. The in vitro half-life of the fibrinolytic enzyme at 37 degrees C was found to be 19 h. The kinetic constants, K-m and V-m of the purified enzyme determined using fibrin as substrate was 0.66 mg/mL and 158.73 U/mL The K-cat and catalytic efficiency of the enzyme was found to be 12.21 min(-1) land 1832 mL/(mg min) respectively. The fibrinolytic enzyme did not show any proteolytic activity towards blood plasma proteins like haemoglobin, gamma-globulins and transferrin. In vitro studies revealed that the fibrinolytic enzyme displayed 38% clot lysis for a period of 3 h which was higher than that displayed by streptokinase and heparin. A total of seven peptide sequences were obtained after the LC-MS/MS-TOF analysis, out of which only four sequences showed 67% homology with the sequences of the other proteases. All these results suggest its novelty and potential application in thrombolytic therapy. (C) 2018 Elsevier B.V. All rights reserved.