Thermodynamic and kinetic studies of protein structure and enzymic mechanisms

(I)脱氧亚精氨酸羟基酶催化eIF5A的基本修饰的最后一步。最近在人类和酵母中分离出了这种酶，并对其基因进行了测序。根据这一序列，该蛋白质被预测含有几个α螺旋重复序列。圆二色谱(CD)测量表明，该蛋白质77%是螺旋的，没有可检测到的β-折叠。二级结构不会因为去除具有催化作用的重要亚铁而改变，也不会因为金属离子结合所涉及的保守的组氨酸或谷氨酸残基的突变而改变。(Kim Y.S.等人，2006) (Ii)共振光散射是一种深奥的技术，它利用了某些生色团的高分子聚集体的吸收带内折射率的复杂行为。最近发表了许多生化分析，声称使用了这种方法。我们已经证明，在这些实验中检测到的大多数散射峰都是虚假的，源于仪器的光电倍增管的性质，而不是来自所研究的分子物种。描述了一种检测这种伪迹的简单方法。(McPhie P.2006) (3)抗体呈递是启动适应性免疫反应的关键步骤，这取决于共刺激分子的表达。免疫增强型寡核苷酸(ODN)可促进这些分子的表达。CD测量表明，其中几个调控ODN含有鸟嘌呤(G)-四元体结构。这些ODN的热处理削弱了它们的调节特性，也破坏了G-四分体。(王杰等2007年) (4)对淀粉样多肽和蛋白质结构的光学研究仍在继续。

(i) Deoxyhypusine hydroxylase catalyses the final step in the essential modification of eIF5A. The enzyme was recently isolated and the gene sequenced in humans and yeast. Based on this sequence, the protein was predicted to contain several alpha helical repeats. Using circular dichroism (CD) measurements we showed that the protein is 77% helical with no detectable beta sheet. The secondary structure was not changed by removal of the catalytically important ferrous iron, nor by the mutation of conserved His or Glu residues involved in binding of the metal ions. (Kim Y.S. et al, 2006) (ii) Resonance light scattering is an esoteric technique, which takes advantage of the complex behavior of the refractive index within the absorbance bands of high molecular aggregates of some chromophores. Recently numerous biochemical assays have been published, which claim to use this methodology. We have shown that most of the scattering peaks detected in these experiments are spurious, arising from the properties of the intrument's photomultiplier, not from the molecular species under study. A simple method for the detection of this artifact has been descibed. (McPhie P. 2006) (iii) Antibody presentation is a key step in the initiation of the adaptive immune response, depending on the expression of costimulatory molecules. Immune-enhancing oligodeoxynucleotides (ODNs)increase the expression of these molecules. CD measurements were used to show that several of these regulatory ODNs contain guanine(G)-tetrad structures. Heat treatment of these ODNs which diminishes their regulatory properties also destroyed the G-tetrads. ((Wang J. et al 2007) (iv) Optical studies on the structures of amyloid peptides and proteins are continuing.