A Change in the 310- to α-Helical Transition Point in the Heptapeptides Containing Sulfur and Selenium
A Change in the 310- to α-Helical Transition Point in the Heptapeptides Containing Sulfur and Selenium
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DOI：
10.1021/cg101604g
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发表时间：
2011-06-01
影响因子：
3.8
通讯作者：
Ramanathan, Gurunath
中科院分区：
文献类型：
--
作者：
Duley, Anju;Nethaji, Munirathinam;Ramanathan, Gurunath
三种七肽Boc-Ala-Leu-Aib-XXX-Ala-Leu-Aib-OMe（其中XXX =肽A中的甲硫氨酸、肽B中的硒代甲硫氨酸和肽C中的S-苄基半胱氨酸）的晶体结构显示混合的3（10）-/α-螺旋构象，R因子分别为6.94、5.79和5.98。所有的结构都在P2（1）2（1）2（1）空间群中求解。在所有这些肽中均观察到3（10）-至a-螺旋转变。螺旋开始为N-末端的3（10）-螺旋片段，然后在残基Aib（3）羰基（O（3））处转变为肽A和C，而对于肽B，转变发生在残基Leu（2）羰基氧（O（2））处。这些肽的晶体中都有水分子，它们在每个晶体中形成不同类型的氢键模式。观察结果表明，在这些短的七肽序列中，3（10）-到α-螺旋的转变是序列依赖性的。
Crystal structures of three heptapeptides Boc-Ala-Leu-Aib-XXX-Ala-Leu-Aib-OMe (where XXX = methionine in peptide A, selenomethionine in peptide B, and S-benzyl cysteine in peptide C) reveal mixed 3(10)-/alpha-helical conformations with R factors of 6.94, 5.79, and 5.98, respectively. All the structures were solved in the P2(1)2(1)2(1) space group. 3(10)- to a-helical transitions are observed in all of these peptides. The helices begin as a 3(10)-helical segment at the N-terminus and then transit for peptides A and C at residue Aib(3) carbonyl (O(3)), while for peptide B the transition occurs at residue Leu(2) carbonyl oxygen (O(2)). There are water molecules associated in the crystal of each of these peptides and they form different types of hydrogen bonding patterns in each crystal. The observations suggest that 3(10)- to alpha-helical transition is sequence dependent in these short heptapeptide sequences.