CAJ | 학술논문

β-酪蛋白是人乳酪蛋白的主要成分，但它在牛乳中的含量却很小。β-酪蛋白在两者中含量的差异，是人乳比牛乳更易消化的原因之一，研究人乳与牛乳β-酪蛋白结构和功能的差异，对研制出更适合婴儿肠道的，新型人乳模拟型婴儿配方奶粉具有指导性的意义。用紫外分光光度法研究人乳β-酪蛋白和牛乳β-酪蛋白的溶解性、巯基含量、乳化性等功能性质，用荧光光谱和红外光谱分析比较两种蛋白的结构特点。两种蛋白等电点十分接近（pH 4.0～5.0），在等电点附近时，人乳β-酪蛋白的溶解性（10.83％）低于牛乳β-酪蛋白（11.83％），而偏离等电点时人乳β-酪蛋白具有更高的溶解性，人乳β-酪蛋白的乳化活性指数（110～140 m2?g －1）高于牛乳β-酪蛋白（70～130 m2?g －1），两种蛋白的表面巯基（S H ）相似[（18.47±0.08）和（18.67±0.17）μmol?g －1]，而牛乳β-酪蛋白总巯基的含量[（47.46±0.23）μmol?g －1]大于人乳β-酪蛋白[（26.17±0.12）μmol?g －1]，两种蛋白官能团相似，均含有β-折叠结构，人乳β-酪蛋白的氢键数量和内部的疏水性均小于牛乳β-酪蛋白。结果表明，人乳β-酪蛋白比牛乳β-酪蛋白具有更少的α-螺旋和β-折叠等二级结构，具有更疏松灵活的三级结构，同时也具有更高的分子的表面活性。
β-락단백시인유락단백적주요성분，단타재우유중적함량각흔소。β-락단백재량자중함량적차이，시인유비우유경역소화적원인지일，연구인유여우유β-락단백결구화공능적차이，대연제출경괄합영인장도적，신형인유모의형영인배방내분구유지도성적의의。용자외분광광도법연구인유β-락단백화우유β-락단백적용해성、구기함량、유화성등공능성질，용형광광보화홍외광보분석비교량충단백적결구특점。량충단백등전점십분접근（pH 4.0～5.0），재등전점부근시，인유β-락단백적용해성（10.83％）저우우유β-락단백（11.83％），이편리등전점시인유β-락단백구유경고적용해성，인유β-락단백적유화활성지수（110～140 m2?g －1）고우우유β-락단백（70～130 m2?g －1），량충단백적표면구기（S H ）상사[（18.47±0.08）화（18.67±0.17）μmol?g －1]，이우유β-락단백총구기적함량[（47.46±0.23）μmol?g －1]대우인유β-락단백[（26.17±0.12）μmol?g －1]，량충단백관능단상사，균함유β-절첩결구，인유β-락단백적경건수량화내부적소수성균소우우유β-락단백。결과표명，인유β-락단백비우유β-락단백구유경소적α-라선화β-절첩등이급결구，구유경소송령활적삼급결구，동시야구유경고적분자적표면활성。
β-casein was the main component of human milk casein ,but the content of β-casein in the bovine milk was less .The difference inβ-casein content of the two samples was one of the reasons why human milk is more digestible than bovine milk . Studying the differences of structure and function in human and bovine milk β-casein can help us develop a new human milk simu-lated infant formula which will be more suitable for the infant gut .The UV spectrophotometer was used to study the solubility , sulfhydryl and emulsification of human milk β-casein and bovine milk β-casein ,Fluorescence spectroscopy and the infrared spec-troscopy were used to study the structural characteristics of human milk β-casein and bovine milk β-casein .The two samples shared a similar isoelectric point (pH 4.0~5.0) ,the solubility of human milk β-casein (10.83% ) was lower than which in bo-vine milkβ-casein (11.83% ) near the pI ,while it was higher when it deviated the pI .The emulsion ability (110~140 m2 ?g -1 ) of human milk β-casein was higher than that in bovine milk β-casein (70~130 m2 ?g -1 ) and surface sulfhydryl group (SH) of two kinds of milk protein were similar [(18.47 ± 0.08)μmol?g -1 and (18.67 ± 0.17)μmol?g -1 ] .The total sulfhydryl group [(47.46 ± 0.23)μmol?g -1 ] in bovine milk β-casein was more than that in human milk β-casein [(26.17 ± 0.12)μmol?g -1 ] . Functional groups in two samples were similar and they both contained beta sheet ,human milkβ-casein had less H-bond and in-ternal hydrophobic than bovine milk β-casein .The results showed that the two samples had similar functional groups ,while hu-man milkβ-casein had much less secondary structure such as α-helix andβ-sheet ,a looser tertiary structure and a better interfa-cial activity .