企鹅珍珠贝蛋白质组成及重金属镉的分布

Protein compositions and distribution of cadmium in Pteria penguin

为了解企鹅珍珠贝蛋白质组成及重金属镉在不同蛋白质组分中的分布特征,对企鹅珍珠贝蛋白质进行分离,利用石墨炉原子吸收光谱法进行镉的检测及用SDS-PAGE和HPSEC技术测定蛋白组分的相对分子质量分布。结果显示：①从企鹅珍珠贝全脏器中分离得到3种主要蛋白质组分,各分离蛋白组分占总蛋白含量分别为肌浆蛋白27.3%、肌原纤维蛋白23.1%、总基质蛋白50.0%（其中酸溶性基质蛋白10.3%,酸不溶性基质蛋白39.7%;碱溶性基质蛋白22.1%,碱不溶性基质蛋白27.9%）。②肌浆蛋白、肌原纤维蛋白、酸溶性和碱溶性基质蛋白的相对分子质量分布存在较大差异,在20~200ku的高分子质量段,肌浆蛋白和肌原纤维蛋白相对分子质量分布范围较宽,组成复杂,酸溶性蛋白和碱溶性蛋白组成较为简单;在2~20ku的低分子质量段,肌浆蛋白和碱溶性蛋白由较多相对分子质量组分构成,而肌原纤维蛋白和酸溶性蛋白组成相对较简单。③总基质蛋白、肌浆蛋白和肌原纤维蛋白中的镉含量与蛋白质含量呈显著正相关（相关系数为0.998 5）,而在各基质蛋白质中,镉的含量与蛋白质含量则呈显著负相关（相关系数为0.996 4）,说明镉在企鹅珍珠贝体内蛋白质中并不是平均分布的,而是有选择性地结合在不同蛋白质组分上,在温和提取条件下,镉与蛋白质的结合态不被破坏,而在极端pH条件下,由于蛋白质变性可能会导致镉从中解离。

The protein composition and distribution of cadmium in different protein composition were investigated in Pteria penguin. The contents of cadmium in different protein compositions which were separated from Pteria penguin were determined by atomic absorption spectrometry （AAS）. Molec- ular weight distribution of different protein were determined by sodium dodecyl sulfonate-polyacrylamide gel electrophoresis （SDS-PAGE） and high performance size exclusion chromatography （HPSEC） chro- matogram. In the present study, three protein compositions were separated from whole viscera of Pteria penguin,and content of each protein component in total protein were 27. 3% sarcoplasmic protein, 23. 1% myofibrillar protein, 50. 0% total matrix protein （there were 10. 3% of acid soluble matrix pro- tein, 39.7 % of acid insoluble matrix protein, 22. 1% of alkali soluble matrix protein and 27. 9 % of alkali insoluble matrix protein in total matrix protein）. There were a large respective divergence in the molecu- lar weight distribution of sarcoplasmic protein, myofibrillar protein and acid/alkali soluble matrix pro- tein,with sarcoplasmic proteins and myofibrillar protein exhibiting wide molecular weight distribution range of 20-200 ku and complex compositions, and acid/alkali soluble matrix protein having simple com- position,while there were complex compositions of sarcoplasmic proteins and alkali soluble matrix pro- tein and simple compositions of myofibrillar protein and acid soluble matrix protein in the low molecular weight range of 2-20 ku. The distribution of cadmium in three major protein compositions including total matrix protein,sarcoplasmic protein and sarcoplasmic protein exihibted a significantly positive correla- tion with contents of proteins （r=0. 998 5）,while the distributions of cadmium in different matrix pro- tein had a significantly negative correlation with contents of proteins（r=0. 996 4）. The results suggested that cadmium did not evenly distribute in protein of Pteria penguin, but selectively combined with dif- ferent protein components, and cadmium can not be dissociated from protein under mild extraction condi- tions,but it was dissociated from protein under extreme pH conditions.