剂量率对辐照牛血清蛋白生化特性和结构的影响

为研究高剂量率对牛血清辐照灭菌中的活性下降的抑制作用,将新生牛血清分别经平均剂量率为60、600 Gy/min钴源和300 k Gy/min电子加速器3种方式辐照30 k Gy后,分析牛血清蛋白的生化特性和结构变化及其与剂量率的关系。结果表明,与未辐照牛血清相比,辐照后蛋白浊度、疏水氨基酸荧光强度、放热峰出峰时间分别从0.742、24.1 u和16.5 min升高至0.802、99.3 u和17.2 min,而蛋白浓度、放热峰温度分别从0.473和76.4℃下降至0.444和74.5℃。电泳分析(SDS-PAGE)显示,600 Gy/min钴源辐照牛血清中相对分子质量为175 k Da和58 k Da的蛋白组分含量明显大于低剂量率辐照牛血清。经扫描电镜(SEM)分析,辐照后牛血清中沉淀部分呈现密集的网络结构,未沉淀部分呈现碎片和球状体混合的形貌结构,低剂量率辐照的样品蛋白球状体形貌不突出。可见高剂量率有抑制辐照灭菌牛血清蛋白分子变性的作用,3种方式中600 Gy/min钴源效果最明显。

Effect of Irradiation Dose Rate on Biochemical Property and Structure of Bovine Serum Protein

Newborn bovine serum was irradiated respectively by 60Co at the average dose rate of 60 Gy/min and 600 Gy/min and by electron accelerator at the average dose rate of 300 kGy/min, then the bovine serum protein biochemical properties and the micro structure were researched to discuss the effect of high dose rate on inhibiting the denaturation of bovine serum protein during the irradiation sterilization process.The results show that compared with the no irradiated bovine serum, protein turbidity, fluorescence intensity of hydrophobic amino acid and exothermic peak time increase respectively from 0.742, 24.1 u and 16.5 min to 0.802, 99.3 u and 17.2 min, but the concentration and exothermic peak temperature decrease from 0.473 and 76.4 ℃ to 0.444 and 74.5 ℃.SDS-PAGE reveals that the protein content of 175 kDa and 58 kDa in 600 Gy/min of 60Co irradiated bovine serum were significantly higher than that in low dose rate irradiated one.The precipitation from irradiated bovine serum shows dense network structure in SEM images, and the soluble fraction presents fragments and globular body mixed morphology structure.The globular shape is not prominent for the sample treated by low dose rate.High dose rate is found to inhibit the effect of irradiation on the denaturation of bovine serum protein, and the effect of 600 Gy/min 60Co source is the most obvious in the three types.