An electronic effect on protein structure
An electronic effect on protein structure
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DOI：
10.1110/ps.0241903
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发表时间：
2003-06-01
期刊：
影响因子：
8
通讯作者：
Raines, RT
中科院分区：
文献类型：
--
作者：
Hinderaker, MP;Raines, RT
众所周知，肽键对反式构象的偏好归因于空间效应。在这里，我们发现含有n -甲酰基的脯氨酸残基（Hi-1- ci -1' = Oi-1），其中Hi-1比Oi-1具有更小的空间位阻，同样倾向于反式构象。因此，肽键对反式构象的偏好不能仅仅用位阻效应来解释。相反，肽键的氧（i-1）与多肽链中随后的羰基碳（C-i'）之间的n -> π *相互作用也有助于这种偏好。在聚脯氨酸II螺旋中，i-1和C-i‘的距离和i-1…C-i’ = O-i的角度尤其有利于这种n—> pi*相互作用。我们提出，这种电子效应为蛋白质结构的这一元素和其他元素提供了实质性的稳定。
The well-known preference of the peptide bond for the trans conformation has been attributed to steric effects. Here, we show that a proline residue with an N-formyl group (Hi-1-Ci-1' = Oi-1), in which Hi-1 presents less steric hindrance than does Oi-1, likewise prefers a trans conformation. Thus, the preference of the peptide bond for the trans conformation cannot be explained by steric effects alone. Rather, an n --> pi* interaction between the oxygen of the peptide bond (Oi-1), and the subsequent carbonyl carbon in the polypeptide chain (C-i') also contributes to this preference. The Oi-1 and C-i' distance and Oi-1...C-i' = O-i angle are especially favorable for such an n --> pi* interaction in a polyproline II helix. We propose that this electronic effect provides substantial stabilization to this and other elements of protein structure.