Influence of tyrosine on the electronic circular dichroism of helical peptides
Influence of tyrosine on the electronic circular dichroism of helical peptides
复制标题
DOI：
10.1021/jp034517j
复制
发表时间：
2003-08-21
影响因子：
3.3
通讯作者：
Hirst, JD
中科院分区：
文献类型：
--
作者：
Bhattacharjee, S;Tóth, G;Hirst, JD
短螺旋肽的研究可以深入了解蛋白质中氨基酸的相互作用及其在蛋白质折叠中的作用。估计螺旋结构的常用方法是远紫外电子圆二色性（CD）。众所周知，芳香侧链如酪氨酸可能影响该区域的CD，但这种残基具有理想的荧光特性，并且经常被纳入肽中。为了研究酪氨酸的构象与其对CD的贡献之间的关系，我们基于分子动力学模拟，从第一性原理计算了一些短丙氨酸螺旋肽的CD。对静态模型的一些分析补充了计算结果。这些理论研究估计，在220 nm处，酪氨酸残基对残基平均椭圆率的贡献可达+/-5000度cm(2) dmol(-1)，最典型的值为1000度cm(2) dmol（-1）。如果不加以修正，这将导致对肽螺旋度的低估5-20%。对于处于反旋美态的酪氨酸侧链，其精确取向与其在220 nm处对CD的贡献之间存在明显的关系。使用CD对含酪氨酸肽的实验进行解释时，应牢记这些发现，最好采用独立的方法来探测酪氨酸的构象状态。
Studies of short helical peptides can provide insights into amino acid interactions in proteins and their role in protein folding. A common method of estimating helical structure is electronic circular dichroism (CD) in the far ultraviolet. It is known that aromatic side chains such as tyrosine may influence CD in this region, but this residue has desirable fluorescent proper-ties and is nevertheless often incorporated into peptides. To investigate the relationship between the conformation of tyrosine and its contribution to the CD, we have calculated the CD of some short alanine-based helical peptides from first principles based on molecular dynamics simulations. The calculations are complemented by some analysis of static models. These theoretical studies estimate that a tyrosine residue may contribute up to +/-5000 deg cm(2) dmol(-1) to the mean residue ellipticity at 220 nm, with the most typical value being 1000 deg cm 2 dmol(-1). If uncorrected, this would lead to an underestimate of the helicity of the peptide of 5-20%. For a tyrosine side chain in the trans rotameric state, there is a discernible relationship between its precise orientation and its contribution to CD at 220 nm. Experiments on tyrosine-containing peptides using CD should be interpreted bearing these findings in mind and, preferably, with an independent approach for probing the conformational states of tyrosine.