Analysis of calcium phosphate cross-linkage in casein micelles by radioactive isotope Professor

用放射性同位素分析酪蛋白胶束中的磷酸钙交联教授

基本信息

批准号：
07660362
负责人：
AOKI Takayoshi
金额：
$ 1.34万
依托单位：
Kagoshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Although calcium and inorganic phosphate (Pi) in bovine casein micelles were at equilibrium with those in soluble form, their properties have not yet been elucidated sufficiently. In this study, the behavior of calcium and Pi in casein micelles was studied using ^<45>Ca and ^<32>P by ultrafiltration, equilibrium dialysis and gel permeation HPLC in the presence of 6M urea. Approximately 30-40% of the calcium and Pi in bovine casein micelles were estimated to be hard to exchanged with those in soluble phase. Then, artificial casein micelles were prepared at a casein concentration of 2.5% with 30-40 mM calcium, 22-27 mM Pi and 10mM citrate using ^<45>Ca and ^<32>P.About 75 and 65% of micellar calcium and Pi in artificial casein micelles were exchanged after dialysis of artificial casein micelles against a simulated milk ultrafiltrate at 4ﾟC for 72h.The percentage of ^<45>Ca and ^<32>P in the fraction of casein aggregates cross-linked by micellar calcium phosphate were 26.9 and 27.6%, which decreased to about 10% after equilibrium dialysis against a simulated milk ultrafiltrate at 4ﾟC for 72h. The proportion of exchanged calcium and Pi in artificial casein micelles during dialysis for 72h were higher at 25ﾟC than at 4ﾟC,suggesting that the exchange of calcium and Pi between diffusible and micellar phases depended on temperature. The effects of calcium and Pi on the formation and properties of casein micelles were also examined using response surface analyzes. The results suggest that the exchange of calcium and phosphate between diffusible and micellar phases proceeds slowly, and a proportion of calcium and Pi in casein micelles is difficult to exchage.

尽管牛胶束中的钙和无机磷酸盐（PI）与固体形式的钙均处于平衡状态，但尚未正确阐明它们的性质。在这项研究中，如果在6M尿素存在下，使用 ^<45> Ca和 ^<32> p对胶束进行了钙和PI的行为。据估计，牛酪蛋白胶束中约有30-40％的钙和PI很难与固相中的钙交换。然后，使用 ^<45> Ca和 ^<45> Ca和 ^<32> P.About 75和65％的胶束钙和PI的胶束和PI在人造情况下以人为的胶束在透过透射的米克斯群体后交换了75和PI，以30-40毫米的钙，22-27毫米Pi和10mm的柠檬酸钙，22-27毫米Pi和10mm柠檬酸含量以2.5％的浓度制备人造胶束。 ^<45> ca和 ^<32> p的百分比在酪蛋白聚集体的比例中，由胶束磷酸钙交联的百分比为26.9和27.6％，在与模拟的乳脂术在4 c c下的透析相当于透析后，在4°C的同等透析后变为10％。在透析期间，在25°C时在人工病例中交换的钙和PI的比例高于4ﾟC时的比例，这表明在扩散和胶束相之间钙和PI的交换取决于温度。还使用响应表面分析检查了钙和PI对病例胶束形成和特性的影响。结果表明，在扩散和胶束相之间的钙和磷酸盐的交换缓慢地进行，并且如果胶束很难交换，则钙和PI的比例。