Burzio L A, Waite J H
Surgical Sealants, Inc., Woburn, Massachusetts 01801, USA.
Protein Sci. 2001 Apr;10(4):735-40. doi: 10.1110/ps.44201.
Tyrosine residues of neuroendocrine peptides are frequently the targets of oxidation reactions, one of which involves hydroxylation to peptidyl-3, 4-dihydroxy-phenyl-L-alanine (DOPA). The reactivity in vitro of peptidyl-DOPA in two neuroendocrine peptides, a neurotensin fragment (pELYENK) and proctolin (RYLPT), was investigated using ultraviolet-visible scanning spectrophotometry and matrix-assisted laser desorption ionization mass spectrometry following oxidation by tyrosinase and periodate. The peptides form covalently coupled dimers and trimers, and their masses are consistent with the presence of diDOPA cross-links. Lysine does not appear to participate in multimer formation because it is efficiently recovered in fragmentation ladders using subtilisin. While multimer formation in the neurotensin-derived peptide can be blocked effectively by adding N-acetyl-DOPA-ethylester to the reaction medium, the DOPA ethylester couples itself four to five times to each peptide.
神经内分泌肽的酪氨酸残基经常是氧化反应的靶点，其中一种反应涉及羟基化形成肽基-3,4-二羟基苯-L-丙氨酸（多巴）。利用紫外可见扫描分光光度法和基质辅助激光解吸电离质谱法，研究了两种神经内分泌肽（一种神经降压素片段（pELYENK）和促肠肌肽（RYLPT））中的肽基多巴在酪氨酸酶和高碘酸盐氧化后的体外反应活性。这些肽形成共价偶联的二聚体和三聚体，其质量与二多巴交联的存在一致。赖氨酸似乎不参与多聚体的形成，因为使用枯草杆菌蛋白酶时，它能在片段梯中有效回收。虽然通过向反应介质中添加N-乙酰多巴乙酯可以有效阻断神经降压素衍生肽中的多聚体形成，但多巴乙酯自身会与每个肽偶联四到五次。
