基于模拟退火算法的蛋白质空间结构预测

模拟退火是一种通用的启发式优化算法，将模拟退火思想用于求解蛋白质结构预测问题，计算结果表明利用SA算法得到的解优于目前常用的遗传算法和MonteCarlo方法．     

大分子构象态的隧道赝自旋模型

本文根据大分了构象理论和实验结果,提出了大分子构象转变的隧道模型,从微观机制出发, 用量子力学和统计力学描述了构象电子体系;讨论了大分子的构象态、能态以及构象转变时所发 生的相变问题,得出了与现有理论和实验一致的结论．     

含有修饰SpA的重组生物膜的表征

通过ＬＢ膜技术将硬脂酸酯修饰的ＳｐＡ嵌入到气液界面的磷脂膜中，并沉积于疏水石英表面形成重组双层生物膜。此重组膜可作为免疫球蛋白的能诱导膜。结果表明，修饰ＳｐＡ表面硬脂酸数目的多少是影响该蛋白构象变化的主要原因。当共嵌入到磷脂单分子膜中时，膜中蛋白质密度增加，且呈现良好的成膜特性，重组膜中ＳｐＡ的活性下降与理解旨酸的修饰及ＳｐＡ在膜中嵌入作用有关。本文还讨论了膜中结合ＩｇＧ的状态。     

钙调蛋白与酸枣仁皂甙A作用的~1H核磁共振谱研究

利用高分辨的１Ｈ核磁共振技术研究了 Ｃａ２＋对钙调蛋白（ＣａＭ）分子构象的影响以及酸枣仁皂甙 Ａ与 ＣａＭ的作用机制。研究结果表明；随着 Ｃａ２＋的加入． ＣａＭ分子的构象处于不断的变化之中。前两个Ｃａ２＋的加入主要结合在ＣａＭ的第Ⅲ，ⅣＣａ２＋结合位点（Ｃ结构域）上，后两个Ｃａ２＋的加入，则主要结合在ＣａＭ分子的第Ⅰ，Ⅱ Ｃａ２＋结合位点（Ｎ结构域〕上：酸枣仁皂甙 Ａ在 ＣａＭ上也有两类结合位点，一类是位于 ＣａＭ分子 Ｎ结构域上，只能结合一个药物分子的高亲合点；另一类是位于ＣａＭ分子Ｃ结构域上的至少能结合两个药物分子的低亲合点。     

Proteolytic generation and aggregation of peptides from transmembrane regions: lung surfactant protein C and amyloid β-peptide

The formation of amyloid fibrils is associated with several devastating diseases in humans and animals, including e.g. Alzheimers disease (AD) and the spongiform encephalopathies. Here, we review and discuss the current knowledge on two amyloid peptides: lung surfactant protein C (SP-C) and the amyloid -peptide (A), implicated in human lung disease and in AD, respectively. Both these hydrophobic peptides are derived from the transmembrane region of their precursor protein, and can transit from a monomeric -helical state to a -sheet fibril. The helices of SP-C and A are composed of amino acid residues with inherently higher propensities for strand than helix conformation. Their helical states are stabilized by a membrane environment, and loss of membrane association thus promotes structural conversion and fibril formation. We speculate that the loss of structural context for sequences with a high propensity for formation of sheets may be a common feature of amyloid formation in general.Received 9 July 2003; received after revision 15 August 2003; accepted 3 September 2003     

Modeling of 3D-structure for regular fragments of low similarity unknown structure proteins

Because it is hard to search similar structure for low similarity unknown structure proteins dimefly from the Protein Data Bank(PDB)database,3D-structure is modeled in this paper for secondary structure regular fragments(α-Helices,β-Strands)of such proteins by the protein secondary structure prediction software,the Basic Local Alignment Search Tool(BLAST)and the side chain construction software SCWRL3.First.the protein secondary structure prediction software is adopted to extract secondary structure fragments from the unknown structure proteins.Then.regular fragments are regulated by BLAST based on comparative modeling,providing main chain configurations.Finally,SCWRL3 is applied to assemble side chains for regular fragments,so that 3D-structure of regular fragments of low similarity un known structure protein is obtained.Regular fragments of several neurotoxins ale used for test.Simulation results show that the prediction errors are less than 0.06nm for regular fragments less than 10 amino acids,implying the simpleness and effectiveness of the proposed method.     

田菁胶糖链结构和反应活性的量子化学研究

用HyperChem 7的PM3方法计算了田菁胶(SGn=1～5)的电子结构，讨论了稳定构象、侧链内旋转势能面及羟基氧和羟基氧负离子的反应活性。结果表明，甘露糖和半乳糖糖基在SG骨架中基本能保持其单体椅式稳定构象，主链二面角Ψ1，旋转对增大主链柔性和主链卷缩成螺旋贡献最大，螺旋圈中链节数n≤10。受原子间相互排斥作用，SGn=5势能面上的低能构象远少于SGn=1势能面上的。SG侧链羟基氧反应活性较强而主链的较弱。     

乙醇对鲍鱼碱性磷酸酶活力与构象的影响

以乙醇为效应物研究对鲍鱼碱性磷酸酶(ALP)活力影响的结果表明．酶的剩余活力随着乙醇浓度增大而迅速下降，乙醇浓度40％可使酶活力完全丧失．说明乙醇对鲍鱼ALP有明显的失活作用，JG50为13％．含较低浓度乙醇(30％)的失活过程是可逆的反应．测定乙醇对酶的失活作用机理．结果表明乙醇对鲍鱼ALP的失活作用是非竞争性机制，说明底物存在不影响乙醇对酶的失活作用．应用荧光光谱、紫外吸收光谱研究鲍鱼ALP经乙醇微扰后的分子构象变化，发现乙醇对酶分子构象有显的影响，酶的内源荧光强度随乙醇浓度增大而增强．荧光发射峰逐渐发生红移．紫外吸收光谱在276nm吸收峰随乙醇浓度增大而增强．这些结果表明．酶蛋白分子中的生色基团残基的微环境发生变化．     

Structure Characterization of the Folding Intermediates of Proteins

ＩｎｔｒｏｄｕｃｔｉｏｎＳｍａｌｌｓｉｎｇｌｅ ｄｏｍａｉｎ ｐｒｏｔｅｉｎｓｕｓｕａｌｌｙｕｎｆｏｌｄｒｅｖｅｒｓｉｂｌｙｂｙａｃｏｏｐｅｒａｔｉｖｅ ｐｒｏｃｅｓｓｉｎｗｈｉｃｈｐａｒｔｉａｌｌｙ ｆｏｌｄｅｄｉｎｔｅｒｍｅｄｉａｔｅｓｂｅｔｗｅｅｎｔｈｅｆｕｌｌｙｆｏｌｄｅｄ ,ｎａｔｉｖｅｓｔａｔｅａｎｄｔｈｅｆｕｌｌｙｕｎｆｏｌｄｅｄｓｔａｔｅａｒｅｎｏｔｓｔａｂｌｅａｔｅｑｕｉｌｉｂｒｉｕｍ .Ｕｎｄｅｒ ｐａｒｔｉｃｕｌａｒｃｏｎｄｉｔｉｏｎｓ ,ｓｏｍｅ ｐｒｏｔｅｉｎｓｈａｖｅｃｏｎｆｏｒ…