標題: | Antioxidant nature of bovine milk beta-lactoglobulin |
作者: | Liu, H. C. Chen, W. L. Mao, S. J. T. 生物科技學系 Department of Biological Science and Technology |
關鍵字: | beta-lactoglobulin;antioxidant activity;mechanism;milk |
公開日期: | 1-二月-2007 |
摘要: | Heating is necessary for processing milk in the dairy industry, which evidently produces a conformational change in beta-lactoglobulin (beta-LG). beta-Lactoglobulin, a major protein that accounts for approximately 10 to 15% of total milk proteins, is a globular protein consisting of 162 AA with a relative molecular mass of 18.4 kDa. The purpose of the present study was to determine the antioxidant role of beta-LG in milk and the possible mechanism involved. We showed that beta-LG is a mild antioxidant whose potency is less than that of vitamin E and probucol (the latter being an antioxidant used for clinical therapy). The conversion of the beta-LG monomer to dimer was responsible, in part, for the mode of action in protecting low- density lipoproteins against copper-induced oxidation. Cross-linking the free thiol groups of beta-LG by heating (100 degrees C for 2 min), or chemically modifying the beta-LG by carboxymethylation to block the thiol groups resulted in a substantial loss of antioxidant activity. The data suggest that Cys-121 plays an essential role in the antioxidant nature of beta-LG. By using an anti-LG antibody affinity column to deplete the beta-LG from milk, we observed from the lost antioxidant activity that beta-LG contributes approximately 50% of the total activity. Because beta-LG is extremely sensitive to thermal denaturation, to maintain its antioxidant nature, dairy products consumed daily should not be overheated in order to maintain its antioxidant nature. |
URI: | http://hdl.handle.net/11536/11145 |
ISSN: | 0022-0302 |
期刊: | JOURNAL OF DAIRY SCIENCE |
Volume: | 90 |
Issue: | 2 |
起始頁: | 547 |
結束頁: | 555 |
顯示於類別: | 期刊論文 |