Expression and analysis of recombinant human prothrombin-2 in Pichia pastoris / 军事医学

ABSTRACT

Objective To prepare recombinant human prothrombin-2 expressed in Pichia pastoris, and assay the enzymatic and clotting activities of prothrombin-2 activated by prothrombin activator ecarin.Methods Human prothrombin-2 gene and Echis carinatus ecarin gene were synthesized separately on the basis of the cDNA sequences published in GenBank.The gene of prothrombin-2 was cloned into the expression vector pPICZαA.The expression vector pPICZαA/prothrombin-2 was transformed into glycoengineered P.pastoris, and then prothrombin-2 engineered P.pastoris was screened.The expression products were induced by methanol, purified by two-step chromatography and identified by diges-tion by PNGase F and analysis of pepetide fingerprint.The ecarin gene was cloned into the expression vector pcDNA3.1. The expression vector pcDNA3.1/Ecarin was transformed into HEK 293T cells and the culture supernatant of HEK 293T/Ecarin was collected.The reaction product of HEK 293T/Ecarin cell culture supernatant and purified prothrombin-2 was analyzed by S-2238,which was the chromogenic substrate for thrombin.Fibrinogen was used to measure blood clotting time. Results The purified protein of P.pastoris expressed prothrombin-2 culture supernatant was 37 ×103 .The relative molecular mass(Mr) of the purified protein was reduced to 35 ×103, which was consistent with the theoretical Mr of prothrombin-2 molecular weight.The purified protein was proved to be prothrombin-2 by peptide fingerprint identification. The purified prothrombin-2 processed by HEK 293T/Ecarin culture supernatant could hydrolyze S-2238 to produce yellow pNA, and D405 of pNA increased with the volume of the processed prothrombin-2 that could promote the plasma coagulation.The blood clotting time was close to that of the thrombin kit.Conclusion Prothrombin-2 is prepared by P.pastoris and activated toα-thrombin by ecarin.This technique may replace the method of extraction of prothrombin from plasma and can be used for the treatment of war wounds or for future clinical research.