天花粉蛋白C-端顺序的测定

采用肼解法、乙内酰硫脲法和羧肽酶法检测了天花粉蛋白的C-端氨基酸有二,分别为Met和Ala借计算机辅助的羧肽酶法, 测定了天花粉蛋白C-端顺序, 其结果显示C-端是非均一的, 有两个未端, 分别为-ArgAsnAsnMetOH和-ArgAsnAsnMetAlaOH.这些结论已经从天花粉蛋白的溴化氰降解物中获得游离的Ala, 和从该蛋白的胰蛋白酶酶解物中分离得与该两顺序相符的两个碎片而完全证实.

C-Terminal sequencing of trichosanthin

The identification of C-terminal amino acid of trichosanthin (T) of Trichosanthes kirilowii was 1st tried by chem. and enzymic methods such as hydrazinolysis, thiohydantoin reaction, and carboxypeptidase hydrolysis. Results were complicated by the possible presence of >1 terminus, i.e. methionine and alanine (Ala), and by side reactions with the chem. reagents. A computer-assisted carboxypeptidase method determine the C-terminal sequence of T. Its C-terminal sequence is heterogeneous and was identified as -ArgAsnAsnMetOH and ArgAsnAsnMetAlaOH. These 2 sequences were confirmed by other experiments In one, some free Ala was always in the CNBr degradation products of T. In the other, 2 fragments from the trypsin digest of T were isolated from fingerprints as well as from HPLC fractions and their sequences were determine by the DABITC/PITC manual method were the same as those determine by computer simulation.n