Synthesis, crystal structure, and molecular conformation of peptide N‐Boc‐L‐Pro‐dehydro‐Phe‐L‐Gly‐OH
Synthesis, crystal structure, and molecular conformation of peptide N‐Boc‐L‐Pro‐dehydro‐Phe‐L‐Gly‐OH
复制标题
肽N-Boc-L-Pro-deHydrogen-Phe-L-Gly-OH的合成、晶体结构和分子构象
作者：
H. C. Patel;T. Singh;Virander S. Chauhan;P. Kaur
通过通常的后处理程序合成肽N-Boc-L-Pro-邻苯二甲酸-Phe-L-Gly-OH，最后将N-Boc-L-Pro-邻苯二甲酸偶联至甘氨酸。该肽的晶体结构为单斜晶系，空间群为P21，a = 8.951（4）<$，B = 5.677（6）<$，c = 21.192（11）<$，β = 96.97（4）°，V = 1069（1）<$3，Z = 2，dm = 1.295（5）Mgm−3，dc = 1.297（4）Mgm−3。通过使用SHELXS 86的直接方法确定结构。通过块对角最小二乘程序将结构精修至对于1002个观察到的反射的R值为0.074。C2 α -C2 β距离为1.33（2）nm是一个合适的双键长度。C2 α -C2 β -C2 γ夹角为133（1）°。肽骨架扭转角为θ1 = −167（1）°、ω0 = 179（1）°、ω 1 = −48（1）°、ω 1 = 137（1）°、ω1 = 175（1）°、ω 2 = 65（2）°、ω 2 = 15（2）°、ω2 = −179（1）°和ω 3 = −166（1）°。这些值表明，Boc基团具有反式-反式构象，而肽骨架采用β转角II构象，该构象通过长度为3.05（1）Å的分子内氢键稳定。含有β-Phe的肽的结构表明β-Phe促进β-转角II构象。Pro残基的五元吡咯烷环采用理想的Cγ-exo构象，扭转角χ 11 = −24（1）°，χ 12 = 34（1）°，χ 13 = −30（1）°，χ 14 = 15（1）°，θ 10 = 6（1）°。侧链扭转角为χ 21 = −1（2）°、χ 22，1 = −176（1）°和χ 22，2 = 8（2）°。C2 α -C2 β -C2 γ的平面相对于苯环平面旋转7（1）°，这表明邻苯二甲酸侧链的原子基本上是共面的。分子沿B轴沿着形成21螺旋轴相关的氢键行。
The peptide N‐Boc‐L‐Pro‐dehydro‐Phe‐L‐Gly‐OH was synthesized by the usual workup procedure and finally coupling the N‐Boc‐L‐Pro‐dehydro‐Phe to glycine. The peptide crystallizes in monoclinic space group P21 with a = 8.951(4) Å, b = 5.677 (6) Å, c = 21.192(11) Å, β = 96.97(4)°, V = 1069(1) Å3, Z = 2, dm = 1.295(5) Mgm−3, and dc = 1.297(4) Mgm−3. The structure was determined by direct methods using SHELXS86. The structure was refined by the block‐diagonal least‐squares procedure to an R value of 0.074 for 1002 observed reflections. The C 2α –C 2β distance of 1.33(2) Å is an appropriate double bond length. The angle C 2α –C 2β –C 2γ is 133(1)°. The peptide backbone torsion angles are θ1 = −167(1)°, ω0 = 179(1)°, ϕ1 = −48(1)°, ψ1 = 137(1)°, ω1 = 175(1)°, ϕ2 = 65(2)°, ψ2 = 15(2)°, ω2 = −179(1)°, and ϕ3 = −166(1)°. These values show that the Boc group has a trans–trans conformation while the peptide backbone adopts a β‐turn II conformation, which is stablized by an intramolecular hydrogen bond of length of 3.05(1) Å. The structures of dehydro‐Phe containing peptides suggest that the dehydro‐Phe promotes the β‐turn II conformation. The five‐membered pyrrolidine ring of the Pro residue adopts an ideal Cγ‐exo conformation with torsion angles χ 11 = −24(1)°, χ 12 = 34(1)°, χ 13 = −30(1)°, χ 14 = 15(1)°, and θ 10 = 6(1)°. The side chain torsion angles in dehydro‐Phe are χ 21 = −1(2)°, χ 22, 1 = −176(1)°, and χ 22, 2 = 8(2)°. The Plane of C 2α –C 2β –C 2γ is rotated with respect to the plane of the phenyl ring at 7(1)°, which indicates that the atoms of the side chain of dehydro‐Phe are essentially coplanar. The molecules form a 21 screw axis related hydrogen‐bonded rows along the b axis.
DOI：
10.1111/j.1399-3011.1980.tb02949.x
发表时间：
1980
期刊：
International journal of peptide and protein research
影响因子：
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作者：
Benedetti,E;Pedone,C;Toniolo,C;Némethy,G;Pottle,MS;Scheraga,HA
通讯作者：
Scheraga,HA