Study On The In Vitro Stability Of Immunoglobulin G Isolated From Pig Serum

Immunoglobulin(Ig) is the specific globulin produced when organism has immunity reaction after it is stimulated by antigens. It plays an important role in animal immunity. This paper is to study the in vitro stability of Immunoglobulin G isolated from pig serum (PIgG) . The results of the study as follows:(1) Within the range of pH4 0-11.0, PIgG was very stable, but when the pH<4.0 or pH>11.0, the stability of PIgG decreased.(2) Thermodynamic analysis indicated that the reaction degree of heat denaturation of PIgG in PB buffer with pH 7.4 was 1.1. At 60 癈 , 65*C, 70 "C , 75 "C and 80"C, D values for PIgG denaturation were 833.33rainN 131.58minN 37.04min ^ 7.32min and 2.54min respectively. Within these temperature ranges, Z value for PIgG denaturation was 7.96*C, apparent active energy was 284.45KJ/mol. PIgG is stable when heating temperature is lower than 65"C.(3) Sucrose exerted protective effect on the PIgG denaturation induced by acid> alkali and heat. This effect was enhanced by the growth of sucrose concentration.(4) In artificial pepsin digestive system with pH2.0, due to the acid denaturation, the PIgG was hydrolyzed wholly, in the system with pH3.0 and 4.0, although not all entirely PIgG could be detected, but the PIgG antibody activities against E.Coli still existed without changing, this indicates that the F(ab' )2 with antigen-binding activity still remain complete during digesting process.In artificial trypsin digestive system with pH7.4, with the increasing content of trypsin and prolonging of digesting time, the entire PIgG decreased gradually. The hydrochloric acid in gastric juice is the main cause of the inactivation of PIgG.(5) When semifinished product of PIgG and the complete feed addingwith PIgG were preserved at room temperature and at 37 respectively, the PIgG was very stable.