Taylor T C, Kimmel J R
Medical Research Service, Veterans Administration, Medical Center, Kansas City, Missouri 64128.
Anal Biochem. 1987 Oct;166(1):194-203. doi: 10.1016/0003-2697(87)90563-x.
Reaction of avian pancreatic polypeptide with an iodine monochloride reagent at both pH 4 and pH 7.5 results in the differential modification of the four tyrosine residues in this peptide hormone. A total of 19 distinct iodinated derivatives were isolated by reverse-phase high-performance liquid chromatography, and their sites of iodination were characterized by both tryptic mapping and leucine aminopeptidase techniques coupled with HPLC. The pH 4 reaction produced 16 derivatives which, overall, represented substantial iodination at each tyrosine residue, whereas the pH 7.5 reaction was more directed, producing only 7 derivatives. Iodination at the C-terminal tyrosineamide 36 predominated at both pH values, and diiodo-Tyr 36 was found in the majority of the pH 7.5 derivatives. The relative of the four tyrosine residues with ICl were as follows: at pH 7.5, Tyr 36 much greater than Tyr 21 much greater than Tyr 27 greater than Tyr 7; at pH 4, Tyr 36 greater than Tyr 27 greater than Tyr 7 greater than Tyr 21.
禽胰多肽在pH 4和pH 7.5条件下与一氯化碘试剂反应，会导致该肽类激素中四个酪氨酸残基发生不同程度的修饰。通过反相高效液相色谱法共分离出19种不同的碘化衍生物，并通过胰蛋白酶图谱分析和亮氨酸氨肽酶技术结合高效液相色谱法对其碘化位点进行了表征。pH 4反应产生了16种衍生物，总体而言，每个酪氨酸残基都有大量碘化，而pH 7.5反应更具方向性，仅产生7种衍生物。在两个pH值下，C末端酪氨酸酰胺36处的碘化均占主导，并且在大多数pH 7.5衍生物中都发现了二碘代-Tyr 36。四个酪氨酸残基与一氯化碘反应的相对活性如下：在pH 7.5时，Tyr 36远大于Tyr 21远大于Tyr 27大于Tyr 7；在pH 4时，Tyr 36大于Tyr 27大于Tyr 7大于Tyr 21。
