Structural characterization of folded pentapeptides containing centrally positioned 尾(R)Val, 纬(R)Val and 纬(S)Val residues

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• 作者：Bhimareddy Dinesh^a ; Krishnayan Basuroy^b ; Narayanaswamy Shamala^b ; ^{shamala@physics.iisc.ernet.in} ; Padmanabhan Balaram^a ; ^{pb@mbu.iisc.ernet.in}
• 关键词：尾 and 纬 Amino acids ; Hybrid peptides ; Backbone expanded helix ; Peptide conformation ; Crystal structures
• 刊名：Tetrahedron
• 出版年：2012
• 期刊代码：107_00404020
• 类别：ch
• 出版时间：10 June, 2012
• 卷：68
• 期：23
• 页码：4374-4380
• 文件大小：748 K

摘要

A cylindrical pore of 鈭?.5 脜 diameter containing a one-dimensional water wire, within the confines of a hydrophobic channel lined with the valine side chain, has been observed in crystals of the peptide Boc-d-Pro-Aib-Val-Aib-Val-OMe (1) (Raghavender et al., 2009, 2010). The synthesis and structural characterization in crystals of three backbone homologated analogues Boc-d-Pro-Aib-尾³(R)Val-Aib-Val-OMe (2), Boc-d-Pro-Aib-纬⁴(R)Val-Aib-Val-OMe (3), Boc-d-Pro-Aib-纬⁴(S)Val-Aib-Val-OMe (4) are described. Crystal structures of peptides 2, 3 and 4 reveal close-packed arrangements in which no pore was formed. In peptides 2 and 3 the N-terminus d-Pro-Aib segment adopted conformations closely related to Type II鈥?尾-turns, while residues 2-4 form one turn of an 伪尾 right-handed C₁₁ helix in 2 and an 伪纬 C₁₂ helix in 3. In peptide 4, a continuous left-handed helical structure was observed with the d-Pro-Aib segment forming a Type III鈥?尾-turn, followed by one turn of a left-handed 伪纬 C₁₂ helix.