This laboratory is interested in the relationship among protein sequence, structure and the mechanisms of protein folding and enzymic reactions. (i) Secondary Structure of Insoluble Proteins. The secondary structure of a protein is estimated by mathematical analysis of its circular dichroism (CD)spectrum. The protein concentration is usually necessary for analysis of CD data. We have found a concentration independent method of structure determination, which involves measurement and deconvolution of the protein's """"""""g-factor"""""""" spectrum, which is the ratio of a samples CD and absorbance spectra. We are using this technique to investigate the structural behaviour of insoluble amyloid and prion proteins(ii) Structure of Cystathionine beta Synthase (with Dr. Edith Wilson Miles, LBG) We are investigating the conformational states of the CBS protein from yeast and their relevance in the enzymatic mechanism. (iii) Structure of Mammalian Sulphotransferases. (Dr. W.B. Jakoby, LBM) The enzymatic activity of a phenol sulphotransferase, from rat liver, has been shown to be regulated by reversible oxidation/reduction of a conserved specific cysteine residue by physiological concentrations of glutathione. Oxdation of cysteine residue 66 inhibits the physiological activity of the enzyme by very tight substrate inhibition. This mechanism may be important under conditions of oxidative stress to the liver.(iv) Structure and behaviour of thyroid hormone receptors (with Dr. Jane Cheng, NCI) Mutations in the hormone binding domain of these proteins change their affinity for hormone and their activity as activators. (v) Conformation of human interferons (with Kathy Zoon and Hana Schmeisser, FDA). We are studying the effect of amino acid substitutions on the secondary and tertiary structures of these cytokines, which show marked variation in their immunological and antiproliferative actions. (vi) Effect of Conformation on Antigenic Activity of synthetic Peptomers from HIV gp120 (with Frank Robey, NIDCR). (vii) Effect of molecular crowding and confinement on protein satbility (with Kenji Sasahara and Allen Minton, NIDDK).
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