Na^+、Ca^(2+)和pH值对鲸鲨皮胶原蛋白热变性温度的影响  

Effects of Metal Ions and pH on Thermal Stability of Whale Sharp (Rhincodon typus) Skin Collagen

作　　者：康俊霞[1] 康永锋[1,2] 包斌[1,2] 陈志华[1] 谢晶[1] 吴文惠[1,2] 

机构地区：[1]上海海洋大学食品学院,上海201306 [2]上海海洋大学海洋科学研究院,上海201306

出　　处：《食品科学》2011年第13期66-70,共5页Food Science

基　　金：上海市自然科学基金项目(10ZR1413800);上海市重点学科建设项目(J50704)

摘　　要：通过差示扫描量热法(DSC)对不同浓度的Na+、Ca2+和pH值对鲸鲨皮I型胶原蛋白和鲸鲨皮Ⅱ型胶原蛋白热变性温度的影响进行系统研究。I型胶原蛋白的特征性紫外吸收波长位于233.05nm,Ⅱ胶原蛋白的特征性紫外吸收波长位于232.90nm和277.88nm。研究胶原蛋白的聚集动力学曲线,发现鲸鲨I型胶原蛋白和鲸鲨Ⅱ型胶原蛋白浊度随时间变化趋势均呈S型,其聚集过程均可分为初始阶段和生长阶段及趋于稳定阶段。通过高灵敏度差示量热扫描仪对鲸鲨I型胶原蛋白和鲸鲨Ⅱ型胶原蛋白的热稳定性进行表征。鲸鲨I型胶原蛋白的热变性温度为40℃,鲸鲨Ⅱ型胶原蛋白热变性温度为62℃。较低浓度的Na+、Ca2+使I型胶原蛋白和Ⅱ型胶原蛋白的热变性温度降低,这可能是由于金属离子的加入影响了胶原蛋白分子之间带电氨基酸残基的相互排斥作用,降低了胶原蛋白的热稳定性;较高浓度的Na+、Ca2+使I型胶原蛋白和Ⅱ型胶原蛋白的变性温度持续降低,这可能是由于金属离子与胶原蛋白分子竞争水分子,从而导致胶原蛋白的不稳定;继续增加Na+、Ca2+金属离子的浓度时,I型胶原蛋白和Ⅱ型胶原蛋白的变性温度由于发生盐析而增加。I型胶原蛋白在强酸强碱处理后,蛋白的吸热变性峰变小甚至消失。Differential scanning calorimetry（DSC） analysis was used to systematically study the effect of different concentrations of Na＋,Ca2＋ and H＋ on the thermal denaturation temperatures of type I and type II collagens from whale sharp skin.The type I collagen had maximum absorption at 233.05 nm and the type II collagen at 232.90 nm and 277.88 nm.Aggregation dynamic analysis indicated that the turbidity of the type I and II collagens exhibited an S-shaped curve with 3 stages including initial stage,growth stage and stable stage.The thermal stability of the two types of collagens was examined by high-sensitivity differential scanning calorimetry.The thermal denaturation temperatures of the type I and II collagens were at 40 and 62 ℃,respectively.Their thermal denaturation temperatures were reduced at low concentrations of Na＋ and Ca2＋.These results indicated that metal ions could affect charged residues in native collagen molecules,thus leading to the reduction in thermal denaturation temperature.At intermediate concentrations of Na＋ and Ca2＋,the thermal denaturation temperature of type I and II collagens revealed a continuous reduction,which suggested that the loss of thermal stability might be due to the competition for water molecules between metal ions and collagen.High concentrations of Na＋ and Ca2＋ resulted in an increase in collagen denaturation temperature due to protein salting out.Extreme pH treatment caused partial denaturation of collagen and the denaturation peak became smaller or even disappeared.

关 键 词：鲸鲨 胶原蛋白 热变性温度 聚集动力学曲线 差示扫描量热分析 

分 类 号：Q518.4[生物学—生物化学] S986.2[农业科学—捕捞与储运]