Studies on stability of immunoglobulin G from cow milk

• Main Authors: Chen, Chao-Cheng, 陳昭誠
• Other Authors: Chang,Hung-Min
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/36565584023752190141

博士 === 國立臺灣大學 === 食品科技研究所 === 86 === The purpose of this study was to discuss the method such as gel filtration chromatography, ion exchange chromatography and affinity chromatography to se parate IgG ( immunoglobulin G ) from bovine milk. The effects of pH value, buf fer composition, heating temperature, protectants, storage condition, protease influence and lipopolysaccharides of microorganisms on IgG activity were inve stigated. Further study related to IgG microencapsulation and Differential Sca nning Caloriemetry were also be discussed. Results showed that the recovery of IgG with marketed affinity gel, gel filtration chromatography and ion exch ange chromatography was 97.1, 94.3 and 74.8, respectively. However, from the p oint of purity, the highest was obtained by the marketed affinity gel, 86.6%, followed by the gel filtration chromatography method, 80.9%, and self-made aff inity gel, 45/3%. The SDS-polysaccharide gel electrophorotograms of purified I gG demanstrated the molecular weight was approximately 160,000. IgG was found to be unstable under pH 4 and above 10. Heat-induced denaturation increased wi th increasing temperature especially at the temperature higher than 95℃. The protection effect of thermal denaturation by glycerol was most remarkable, fol lowed by the fructose and maltose addition. The activation energy of IgG, IgG+ 20% maltose, IgG+0.2% glutamic acid, IgG+10% milk powder and IgG+20% glycerol at temperature between 70-80℃ was innvestigated to be 328.4, 280.3, 300.5, 28 9.4 and 265.4 KJ/mole, respectively. Spray-dried ( 130℃ ) method inactivated IgG significantly, and the addition of arabia gum to IgG was found to be less effective in protecting IgG from heat denaturation. Freeze-dried IgG was susce ptible to protease. The residual IgG activity was lowest at pH 2, followed by pH 3 and 4 when was hydrolyzed by pepsin at S/E ratio 1/20. The bands of IgG h eavy chain in SDS-polysaccharide gel electrophoretograms decreased with increa sing protease reaction time.Storage temperature and period, and light exposure affected the residual activity of purified IgG. The purified IgG was most sen sitive to E. coli O111:B4, followed by E. coli O55:B5 when detected by ELISA m ethod with the microorganism species tested in the experiment. IgG treated wit h trypsin showed remarkable reduction in activity detected by ELISA.