Chou K C, Blinn J R
Pharmacia & Upjohn, Kalamazoo, Michigan 49007-4940, USA.
J Protein Chem. 1997 Aug;16(6):575-95. doi: 10.1023/a:1026366706677.
Although a beta-turn consists of only four amino acids, it assumes many different types in proteins. Is this basically dependent on the tetrapeptide sequence alone or is it due to a variety of interactions with the other part of a protein? To answer this question, a residue-coupled model is proposed that can reflect the sequence-coupling effect for a tetrapeptide in not only a beta-turn or non-beta-turn, but also different types of a beta-turn. The predicted results by the model for 6022 tetrapeptides indicate that the rates of correct prediction for beta-turn types I, I', II, II', VI, and VIII and non-beta-turns are 68.54%, 93.60%, 85.19%, 97.75%, 100%, 88.75%, and 61.02%, respectively. Each of these seven rates is significantly higher than 1/7 = 14.29%, the completely randomized rate, implying that the formation of different beta-turn types or non-beta-turns is considerably correlated with the sequences of a tetrapeptide.
尽管β-转角仅由四个氨基酸组成，但它在蛋白质中呈现出多种不同类型。这主要仅取决于四肽序列，还是由于与蛋白质其他部分的多种相互作用所致？为回答这个问题，提出了一种残基偶联模型，该模型不仅可以反映四肽在β-转角或非β-转角中，而且可以反映在不同类型β-转角中的序列偶联效应。该模型对6022个四肽的预测结果表明，对I型、I'型、II型、II'型、VI型和VIII型β-转角以及非β-转角的正确预测率分别为68.54%、93.60%、85.19%、97.75%、100%、88.75%和61.02%。这七个比率中的每一个都显著高于完全随机比率1/7 = 14.29%，这意味着不同类型的β-转角或非β-转角的形成与四肽序列密切相关。
