The diversity of biological functions expressed by proteins arises from their different three-dimensional structures. Therefore, the key to understanding the catalytic action of these macromolecules is to discover the underlying structure – function relationships that produce a particular activity. To achieve this goal, our laboratory is keenly interested in elucidating the high resolution atomic structures of proteins using X-ray diffraction techniques.
To obtain an even clearer understanding of the mechanistic issues involved in enzymatic activities, we also pursue the study of protein complexes with substrates, inhibitors, transition state analogues and even other proteins. These additional types of studies provide exciting new information on the functioning of proteins that is not accessible by other methods. We also obtain further mechanistic insight into biological function through the combined use of structure-function-mutagenesis analyses. In this way the controlled and systematic replacement of key functional and structural amino acids allows for a truly comprehensive understanding of the roles of individual amino acids. To assist in this process, structural modeling on molecular graphics workstations is used to design mutant proteins with specific properties before they are generated in the laboratory. By combining all the available structural and functional information, our laboratory then seeks to apply this knowledge in the development of novel enzyme inhibitors that have the potential of being human therapeutic drugs.
Overall, the current research effort in our laboratory is focused on two proteins. The first involves the critical digestive enzyme human pancreatic alpha-amylase, with the immediate goals of determining the catalytic mechanism of this enzyme and how substrates bind in the active site region next to catalytic residues. As part of this process our laboratory has solved the full three-dimensional atomic structure of human pancreatic alpha-amylase. This structural information, in combination with other functional studies, is being used as the starting point for the design of inhibitors to act as therapeutic drug agents in the treatment of diabetes, obesity and dental caries.
A second system being examined involves the unique multi-functional protein Hsp27, which plays a role in the progress of prostate cancer. Here the goals are to solve the three-dimensional structure of this oligomeric protein and then use this information in the design of inhibitory therapeutics. Also in progress is a search of chemical and natural extract libraries to discover additional novel inhibitory motifs that can assist in this drug discovery process.
Further details concerning research in our laboratory can be found in “Publications”.
Duckworth H, Nguyen N, Gao Y, Donald L, Maurus R, Ayed A, Bruneau B, Brayer G, “Enzyme-Substrate Complexes of Allosteric Citrate Synthase: Evidence for a Novel Intermediate in Substrate Binding”, Biochimica Biophysica Acta, 1834, 2546-2553 (2013)
Caner S, Nguyen N, Aguda A, Zhang R, Pan Y, Withers S, Brayer G., “The Structure of the Mycobacterium smegmatis Trehalose Synthase Reveals an Unusual Active Site Configuration and Acarbose-Binding Mode”, Glycobiology, 23, 1075-1083 (2012)
Williams L, Li C, Withers S, Brayer G, “Order and Disorder: Differential Structural Impacts of Myricetin and Ethyl Caffeate on Human Amylase, an Antidiabetic Target”, J. Med. Chem., 55, 10177-10186 (2011)
Zhang R, Pan Y, He S, Lam M, Brayer G, Elbein A, Withers S, “Mechanistic Analysis of Trehalose Synthase from Mycobacterium smegmatis”, J. Biol. Chem., 286, 35601-35609 (2009)
Zhang R, Li C, Williams L, Rempel B, Brayer G, Withers S, “Directed ‘in situ’ Inhibitor Elongation as a Strategy to Structurally Characterize the Covalent Glycosyl-Enzyme Intermediate of Human Pancreatic Alpha-Amylase”, Biochemistry, 48, 10752-10764 (2009)
Dalal K*, Nguyen N, Alami M, Tan J, Moraes T, Lee W, Maurus R, Sligar S, Brayer G, Duong, F, “Structure, Binding and Activity of Syd, a SecY-interacting Protein”, J. Biol. Chem. 284; also discussed in News and Views, Nature Structural & Molecular Biology 16, 106 (2009), 284, 7897-7902