Thermodynamic and kinetic studies of protein structure and enzymic mechanisms

(i)脱氧hypusine羟化酶催化了eIF5A本质修饰的最后一步。这种酶最近被分离出来，并在人类和酵母中进行了基因测序。根据该序列，预测该蛋白含有几个α螺旋重复序列。利用圆二色性（CD）测量，我们发现蛋白质是77%的螺旋状，没有检测到β片。二级结构不会因去除催化重要的亚铁而改变，也不会因涉及金属离子结合的保守的His或Glu残基的突变而改变。（Kim ys et al ., 2006）

(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.