Karle I L, Flippen-Anderson J L, Uma K, Balaram P
Laboratory for the Structure of Matter, Naval Research Laboratory, Washington, DC 20375-5000.
Proc Natl Acad Sci U S A. 1990 Oct;87(20):7921-5. doi: 10.1073/pnas.87.20.7921.
The crystal structure of the decapeptide Boc-Aib-Glu(OBzl)-Leu-Aib-Ala-Leu-Aib-Ala-Lys(Z)-Aib-OMe (where Aib is alpha-aminoisobutyryl, Boc is t-butoxycarbonyl, OBzl is benzyl ester, and Z is benzyloxycarbonyl) illustrates a parallel zipper arrangement of interacting helical peptide columns. Head-to-tail NH...OC hydrogen bonding extends the alpha-helices formed by the decapeptide into long columns in the crystal. An additional NH...OC hydrogen bond in the head-to-tail region, between the extended side chains of Glu(OBzl), residue 2 in one molecule, and Lys(Z), residue 9 in another molecule, forms a "double tooth" on the side of the column. These double teeth are repeated regularly on the helical columns with spaces of six residues between them (approximately 10 A). The double teeth on a pair of parallel columns (all carbonyl groups pointed in the same direction) interdigitate in a zipper motif. All contacts in the zipper portion are of the van der Waals type. The peptide, with formula C66H103N11O17.H2O, crystallizes in space group P2(1)2(1)2(1) with a = 10.677(4) A, b = 16.452(6) A, and c = 43.779(13) A; overall agreement R = 10.2% for 3527 observed reflections (magnitude of /F0/ greater than 3 sigma); resolution 0.9 A.
十肽Boc-Aib-Glu(OBzl)-Leu-Aib-Ala-Leu-Aib-Ala-Lys(Z)-Aib-OMe（其中Aib为α-氨基异丁酰基，Boc为叔丁氧羰基，OBzl为苄酯，Z为苄氧羰基）的晶体结构显示出相互作用的螺旋肽柱的平行拉链排列。头对尾的NH...OC氢键将由十肽形成的α-螺旋延伸到晶体中的长柱中。在头对尾区域，一个分子中的第2位残基Glu(OBzl)的延伸侧链与另一个分子中的第9位残基Lys(Z)之间存在额外的NH...OC氢键，在柱的一侧形成一个“双齿”。这些双齿在螺旋柱上规则重复，它们之间相隔六个残基（约10 Å）。一对平行柱上的双齿（所有羰基指向同一方向）以拉链基序相互交错。拉链部分的所有接触都是范德华类型。该肽的化学式为C66H103N11O17.H2O，结晶于空间群P2(1)2(1)2(1)中，a = 10.677(4) Å，b = 16.452(6) Å，c = 43.779(13) Å；对于3527个观测反射（/F0/大于3σ），总体一致性R = 10.2%；分辨率为0.9 Å。
