Wilson D R, Finlay B B
Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada.
Protein Eng. 1997 May;10(5):519-29. doi: 10.1093/protein/10.5.519.
Analyses of databases derived from the Brookhaven Protein Data Bank have identified a set of related turn structures formed by the sequence Asx-Pro-Xxx(n). In a variety of flanking structural contexts, more than 60% of Asx-Pro sequences adopt a turn conformation stabilized by a set of alternative hydrogen bonds among the side chain O delta and backbone C = O carbonyl oxygens of Asx (residue i) and the backbone NH of residues i + 2, i + 3 and in some cases i + 4. In contrast, the structures adopted by Ser-Pro, His-Pro and other Xxx-Pro sequences reflect more heterogeneous hydrogen-bonding patterns. As expected, structures formed by Asx-Pro-Asx are similar to those formed by Asx-Pro-Xxx(n), but in some cases additional hydrogen bonds are formed between the Asx side chains. Hydrogen bond patterns within Asx-Pro and Asn-Pro-Asn turns are consistent with published NMR studies of helical (Asn-Pro-Asn-Ala)n peptides, indicating that a consensus structure reflecting these hydrogen bonds can serve as a partial model of the Asn-Pro-Asn-Ala tetrapeptide repeats of Plasmodium falciparum circumsporozoite protein.
对源自布鲁克海文蛋白质数据库的数据库分析已鉴定出一组由序列Asx-Pro-Xxx(n)形成的相关转角结构。在各种侧翼结构环境中，超过60%的Asx-Pro序列采用一种转角构象，该构象由Asx（残基i）的侧链Oδ与主链C=O羰基氧以及残基i+2、i+3（在某些情况下还有i+4）的主链NH之间的一组替代氢键稳定。相比之下，Ser-Pro、His-Pro和其他Xxx-Pro序列所采用的结构反映出更多样化的氢键模式。正如预期的那样，Asx-Pro-Asx形成的结构与Asx-Pro-Xxx(n)形成的结构相似，但在某些情况下，Asx侧链之间会形成额外的氢键。Asx-Pro和Asn-Pro-Asn转角内的氢键模式与已发表的螺旋(Asn-Pro-Asn-Ala)n肽的NMR研究一致，表明反映这些氢键的共有结构可作为恶性疟原虫环子孢子蛋白Asn-Pro-Asn-Ala四肽重复序列的部分模型。
