The dipeptide and tripeptide analogues salicyl-L-aspartic acid (Sal-L-Asp) and salicylglycyl-L-aspartic acid (SalGly-L-Asp) were synthesized and their protonation and complex formation with VIVO2+ were studied in aqueous solution through the use of pH-potentiometry and spectroscopic (UV-Vis, CD and EPR) techniques. The phenolate terminus proved to be a good anchoring site to promote (i) the metal ion-induced deprotonation and subsequent coordination of the peptide amide group(s) in the pH range 4–5 for the dipeptide analogue, (ii) and in the pH range 5–6 in a very cooperative way for the tripeptide analogue. The results suggest that the presence of good anchoring donors on both sides of the amide groups is responsible for the cooperative deprotonation of the two amide-NH groups.
合成了二肽和三肽类似物
水杨酸-
L-天冬氨酸(Sal-L-Asp)和
水杨酸甘
氨酸-
L-天冬氨酸(SalGly-L-Asp),并在
水溶液中通过pH-电位法和光谱学(紫外-可见光,圆二色性和电子顺磁共振)技术研究了它们的质子化和与VIVO2+的配合形成。在pH范围4–5时,
酚酸端证明是一个良好的锚定位点,促进了二肽类似物中
金属离子诱导的去质子化及随后的肽酰胺基团的配位;在pH范围5–6时,对于三肽类似物以非常协同的方式进行。结果表明,酰胺基团两侧良好的锚定供体的存在,是造成两个酰胺-NH基团协同去质子化的原因。