FACTORS AFFECTING THE SECONDARY STRUCTURE IN PROTEINS

描述：通常认为， 蛋白质决定其最终的三维结构。 研究人员 已经注意到某些氨基酸对给定的二级结构具有偏好， 结构，已经开发了许多使用氨基酸 从一级序列预测二级结构的偏好。 然而，在这方面， 20年的研究使它比原来的改进很小 预测方案，今天的理论仍然是大约70%的准确率。 在最后一次授予期间，除了显示 考虑到氨基酸的序列， 序列（或所研究的肽中的散装溶剂）也必须 考虑了 显然，预测算法必须采取微溶剂， 预测时考虑三级结构中的非局部氨基酸 二级结构 α-螺旋成核假说也是 研究;一个假设，指出只有少数残基与 α-螺旋结构强烈倾向引发其形成， 通过不同的序列传播结构，直到强断路器 终止两端的增长。 被调查的系统没有遵守 成核假说，表明平均倾向近 二级结构的邻居驱动其形成。 前两 这里列出的具体目标是进行研究的明显结果 在过去的一段时间里， 最后一个具体目标继续长期 约翰逊博士的长期兴趣，在有关的圆二色性， 蛋白质的二级结构，但这是一个次要目标。 1. 建议调查每个构象的偏好 已用于稳定的溶剂系统中的氨基酸 α-螺旋和β-链结构。 2. 建议调查 氨基酸偏好的哪些变化是必要的， 序列形成α螺旋或β链。 3. 提出要 用圆二色性研究蛋白质的二级结构， 目前的兴趣，并改善分析光盘系统，为中学 结构

DESCRIPTION: It is generally accepted that the amino acid sequence of a protein determines its ultimate three-dimensional structure. Researchers have noted that certain amino acids have a preference for a given secondary structure, and a number of schemes have been developed that use amino acid preferences to predict secondary structure from primary sequence. However, twenty years of research has led to little improvement over the original predictive schemes, and today theory remains about 70 percent accurate. During the last granting period, it was shown that in addition to considering the sequence of amino acids, the environment seen by the sequence (or bulk solvent in the peptides under study) must also be considered. Apparently, predictive algorithms must take the microsolvent of non-local amino acids in the tertiary structure into account when predicting secondary structure. The alpha-helix nucleation hypothesis was also investigated; a hypothesis that states that only a few residues with a strong propensity for alpha-helix structure initiate its formation and propagate the structure through indifferent sequences until strong breakers terminate the growth on both ends. The system investigated did not obey the nucleation hypothesis, indicating that the average propensity of near neighbors for secondary structure drive its formation. The first two specific aims listed here are the obvious sequels to the research carried out over the past granting period. The last specific aim continues the long standing interest of Dr. Johnson in relating the circular dichroism of proteins to their secondary structure, but this is a secondary goal. 1. It is proposed to investigate the conformational preferences of each amino acid in the solvent systems that have been used to stabilize alpha-helix and beta-strand structures. 2. It is proposed to investigate what changes in amino acid preferences are necessary for indifferent sequences to form an alpha helix or a beta-strand. 3. It is proposed to use circular dichroism to investigate the secondary structure of proteins of current interest, and to improve the system of analyzing CD for secondary structure.