晶体中的合成肽螺旋：两种异构十肽中α-螺旋的结构、反平行和平行排列基序

Synthetic peptide helices in crystals: structure and antiparallel and skewed packing motifs for alpha-helices in two isomeric decapeptides.

作者信息

Karle I L, Flippen-Anderson J L, Uma K, Balaram P

机构信息

Laboratory for the Structure of Matter, Naval Research Laboratory, Washington, DC 20375-5000.

出版信息

Biopolymers. 1990;30(7-8):719-31. doi: 10.1002/bip.360300707.

DOI:10.1002/bip.360300707

PMID:2275974

Abstract

The isomeric decapeptides Boc-Aib-Ala-Leu-Ala-Aib-Aib-Leu-Ala-Leu-Aib-OMe (II) and Boc-Aib-Ala-Aib-Ala-Leu-Ala-Leu-Aib-Leu-Aib-OMe (III), are predominantly alpha-helical with little effect on the conformation with interchange of Aib/Ala residues or Aib/Leu residues. The packing motif of helices in crystal II is antiparallel, whereas the helices pack in a skewed fashion in crystal III, with a 40 degrees angle between neighboring helix axes. Crystal III contains a water molecule in a hydrophobic hole that forms hydrogen bonds with two carbonyl oxygens that also participate in 5----1 type hydrogen bonds. Values for helical torsional angles phi and psi assume a much wider range than anticipated. Crystal II: C49H88N10O13, space group P2(1), with a = 16.625 (2) A, b = 9.811 (5) A, c = 18.412 (3) A, beta = 99.79 (1) degrees, Z = 2, R = 5.7% for 4338 data with magnitude of F0' greater than 3 sigma(F). Crystal III: C49H88N10O13 x 1/2H2O, space group P2(1) with a = 11.072 (2) A, b = 34.663 (5) A, c = 16.446 (3) A, beta = 107.85 (1) degrees, Z = 4, R = 8.3% for 6087 data with [F0[ greater than 3 sigma(F).

摘要

同分异构的十肽Boc-Aib-Ala-Leu-Ala-Aib-Aib-Leu-Ala-Leu-Aib-OMe（II）和Boc-Aib-Ala-Aib-Ala-Leu-Ala-Leu-Aib-Leu-Aib-OMe（III）主要呈α-螺旋结构，Aib/Ala残基或Aib/Leu残基互换对其构象影响很小。晶体II中螺旋的堆积基序是反平行的，而在晶体III中螺旋以倾斜方式堆积，相邻螺旋轴之间有40度角。晶体III在一个疏水孔中含有一个水分子，该水分子与两个羰基氧形成氢键，这两个羰基氧也参与5----1型氢键。螺旋扭转角φ和ψ的值所呈现的范围比预期的要宽得多。晶体II：C49H88N10O13，空间群P2(1)，a = 16.625 (2) Å，b = 9.811 (5) Å，c = 18.412 (3) Å，β = 99.79 (1)度，Z = 2，对于4338个|F0'|大于3σ(F)的数据，R = 5.7%。晶体III：C49H88N10O13·1/2H2O，空间群P2(1)，a = 11.072 (2) Å，b = 34.663 (5) Å，c = 16.446 (3) Å，β = 107.85 (1)度，Z = 4，对于6087个|[F0|大于3σ(F)的数据，R = 8.3%。