Purification and isolation of alpha-I-proteinase inhibitor and determination of some of it's physicochemical properties

We used a method to prepare the alpha-I-proteinase inhibitor (AIPI) from the enriched Chon IV-1 paste, without complex steps and expensive chemical materials in a simple condition. The purification and isolation of the AIPI from human plasma and the determination of some of its physicochemical properties were the aims of this study. Firstly, the AIPI was separated from other proteins in the IV-l paste by two times precipitation by the polyethylene glycol. Secondly, using the ion exchange chromatography on the DEAE-Sepharose-CL6B gel the AIPI was obtained with a higher purity. The virus inactivation by the pasteurization at 60°C for 10 hours was carried out without any significant changes in the biological activity. The final product was concentrated by the ultra-filteration and lyophilized. The activity of the AlPI was determined based on it's trypsin inhibitory capacity (TIC). The single-radial immuno-diffusion (SRID) was also carried out to estimate the amount of the AIPI. The results showed an AIPI purity of 0.62 with a 60 percent yield with a molecular weight determined to be about 54000 Dalton by the SDS-PAGE. For a more precise calculation of the degree of purity and confirming the antigenic property, the immuno-electrophoresis method was used against the human antiserum and the specific antiserum of the AIPI. Stoichiometric studies between the AIPI and trypsin showed that an amount of 1.5 to 2 ug of this protein is able to inhibit 1 ug of trypsin. The inhibitory properly of the purified AIPI was comparable with the commercial product used in this regard.