含有甘氨酸和L-脯氨酸多肽的转角结构研究

Study on the turn structure of polypeptides containing glycine and L-proline

肽链转角结构的形成与其结构中分子内氢键的存在有着直接关系,可通过检测肽链中分子内氢键的存在情况对肽链转角结构进行研究。为了深入研究具有转角结构的肽类化合物,以甘氨酸、L-脯氨酸为原料,叔丁氧羰基和苯胺为封端基团,在HBTU,HATU缩合剂的作用下制备了2种三肽和3种四肽。通过^1H NMR,IR及MS对合成产物进行结构表征,用核磁共振等梯度变温氢谱实验对合成的多肽分子内氢键进行检测,用^1H-^1H NOE对形成的分子内氢键的羰基位置进行推测。实验表明：在合成的5种多肽中,有3种多肽形成了分子内氢键,2种未形成。在形成分子内氢键的多肽中都有-Gly-L-Pro-Gly-片段,而只有-L-Pro-Gly-或-Gly-L-Pro-片段的多肽未形成分子内氢键;形成分子内氢键的羰基位置为与苯胺氮氢相连的羰基,形成分子内氢键的氮氢位置为与叔丁氧羰基相连的氮氢。

The formation of turn structure in peptide chains has direct relations with intramolecular hydrogen bonds,therefore the existence of this bond can be tested to research the turn structure.Herein,two tripeptides and three tetrapeptides are synthesized by using glycine and L-proline as raw materials,t-butoxycarbonyl and aniline as capping groups,and HBTU and HATU as condensation reagents.^1H NMR,IR and MS are adopted to characterize the structure of the products.Constant-gradient and variable-temperature ^1H NMR spectra test is used to detect the intramolecular hydrogen bond of the synthesized polypeptides,and ^1H-^1H NOE is used for the speculation of the carbonyl group location of intramolecular hydrogen bond.The test illustrates that intramolecular hydrogen bond is found in three out of the five synthesized polypeptides,and it is not found in the other two.The polypeptides with intramolecular hydrogen bond formed all have the ＂-Gly-L-Pro-Gly-＂ segment,while the pol-ypeptides with only ＂-L-Pro-Gly-＂ segment or ＂-Gly-L-Pro-＂ segment do not have intramolecular hydrogen bond formed.The carbonyl group forming of intramolecular hydrogen bond is attached to the amino group of the capping aniline,and amino group involved in hydrogen bond formation is linked to t-butoxycarbonyl.