明胶大分子的还原性与抽提的关系

A STUDY OF THE REDUCING POWER CHANGE OF PHOTOGELATINS IN DEPENDENCE ON THEIR EXTRACTION DEPTH

用不同抽提次序的一系列明胶样品,用电位法测定了它们的还原性,用氨基酸分析仪测定了蛋氟酸(Met)、蛋氨酸亚砜(Metsox)和砜(Metson)的含量,用SDS-PAGE电泳法测定了它们的不同构象组份的相对含量。发现:明胶的还原性随抽提次序的增加出现一极大值,而这个极大值与α_1,α_1+α_2和α_1/α_2的比值互呈正并行性的对应关系。仔细考察和对比α_1和α_2的一级构型表明:α_1比α_2含有较多的Met。这个极大值的出现,是与第2道抽提出来的明胶中含有较多的α_1组份(从而较多的Met)有关。

A series of photogelatin samples extracted for different times was collected, The reducing power (RP) was determined by potential titration method, the Methionine, Metsox and Metson contents were evaluated with L-8500 amino acid analyzer, the molecular weight distribution of the different conformation components contained in different extracts (No. 1-5) was found with SDS-PAGE method. It was shown that a maximum was found on the curve of RP versus extraction depth and a parallel relationship was demonstrated between RP and the α1, α1 + α2 or α1/α2. This parallel relationship can be elucidated by the following 2 main points: (1) α1 chain contains higher content of Met than that of α2 chain, which can be clearly seen from their primary structure of amino acid sequence; (2) among the extracted gelatings (No.1-5)only the gelatin of the 2nd extract ranks the 1st containing the highest content of α1 conformation component. The discovery and the elucidation of the parallel relationship between RP and extraction depth are of significance in the classification and specification of photogelatins and in making full and reasonable use of different gelatin-extracts in various specified circumstances.