Usefulness of the Peptide Segment Separation Method for Asparagine-Rich Protein Syntheses. Synthesis of Malaria Vaccine Analogs Having the Repeated Unit of L-Asparaginyl-L-Alanyl-L-Asparaginyl-L-Prolyl
作者:Mitsuaki Narita、Hitoshi Takegahara、Seiji Ono、Hisaya Sato
DOI:10.1246/bcsj.63.484
日期:1990.2
In order to demonstrate the usefulness of “the peptide segment separation method” for syntheses of Asn-rich proteins, the central area of circumsporozoite protein of human malaria parasite plasmodium falciparum, Boc–(Asn–Ala–Asn–Pro)n–OBzl (n=2, 3, 4, 6, 9, 12, and 18), were prepared by the coupling reactions of H–(Asn–Ala–Asn–Pro)k–OBzl (k=1, 2, 3, 6, 9, and 12) with Boc–(Asn–Ala–Asn–Pro)m–OH (m=1, 3, or 6) using DCC and HOBt as coupling reagents. The peptide chains are separated into peptide segments by the tertiary peptide bonds of Asn–Pro moieties and they are assembled by the sequence of Asn–Ala–Asn separated by a Pro residue. Regardless of the increase in the peptide chain lengths of the amino and carboxyl components, the coupling reactions in DMF or NMP were achieved in high yields. The excellent solubility of the peptides in highly polar solvents was preserved in spite of the tendency for an Asn residue to have a high potential for aggregation through hydrogen bond formed by the side-chain amide group. The purification of the peptide series by recrystallization could be completely achieved and HPLC on a gel filtration column showed all the peptides to be monodisperse.
为了证明“肽段分离方法”在合成富含天冬酰胺(Asn)蛋白中的有效性,研究人员合成了人类疟疾寄生虫 Plasmodium falciparum 的环孢子蛋白的中心区域 Boc–(Asn–Ala–Asn–Pro)n–OBzl(n=2, 3, 4, 6, 9, 12 和 18),通过将 H–(Asn–Ala–Asn–Pro)k–OBzl(k=1, 2, 3, 6, 9 和 12)与 Boc–(Asn–Ala–Asn–Pro)m–OH(m=1, 3 或 6)在 DCC 和 HOBt 的催化下进行偶联反应制备。肽链通过天冬酰胺-脯氨酸(Asn–Pro)部分的三级肽键被分离为肽段,并且它们按天冬酰胺-丙氨酸-天冬酰胺的顺序组装,肽段之间由脯氨酸残基分隔。尽管氨基和羧基组分的肽链长度增加,但在 DMF 或 NMP 中的偶联反应仍然获得了高产率。尽管天冬酰胺残基容易通过侧链酰胺基团形成氢键而聚集,但肽在高极性溶剂中的优良溶解性仍得以保持。通过重新结晶对肽系列进行的纯化完全成功,且在凝胶过滤柱上的高效液相色谱(HPLC)显示所有肽均为单分散。