This CAREER award in the Inorganic, Bioinorganic and Organometallic Chemistry program in the Division of Chemistry in the Directorate for Mathematics and Physical Sciences and the Molecular and Cellular Biosciences program in the Molecular & Cell BIology Division of the Directorate for Biological Sciences supports research by Professor David Huffman at Western Michigan University to elucidate the inorganic chemistry responsible for the cellular transport of copper by determining the nature of putative three-coordinate intermediate copper complex that forms when the metallochaperone (HAH1) transfers copper to the target domain in the Wilson protein (WLN4). Ag(I) will be used as a spectroscopic probe of Cu(I), since the thiolate chemistry of Ag(I) and Cu(I) are similar. XANES and EXAFS experiments of these proteins show that these motifs can chelate copper in a two-coordinate digonal or a three-coordinate trigonal environment when exogenous thiols are present. In the NMR and X-ray structures, the methionine found in the MXCXXC copper-binding motif is buried in the hydrophobic core of the protein. Methods to be used are: (1) Producing mutants of each protein in which the least accessible thiol is mutated, as a means of trapping the Cu(I) intermediate. (2) Titrations between Cu(I)-HAH1 and WLN4 and also between Cu(I)-WLN4 and HAH1, to be monitored by UV, XANES/EXAFS, and NMR. Similar experiments will replace Cu(I) with Ag(I), since Ag(I) complexes are less labile and 109Ag can be an NMR probe in the HAH1/WLN4 complex. (3) The synthesis of models complexes of Cu(I) and Ag(I) to be used as standards for the UV titrations and XANES experiments. A challenge will be to make trigonal aliphatic thiolate complexes of Cu(I) and Ag(I).
The educational component is to expand the training of under-represented students in the sciences, both locally and abroad, and to make WMU biochemistry students more aware of science-related careers. Several approaches will be undertaken: (1) the training of students and interactions with professors from Egerton University in Kenya in collaboration with WMU Haenicke Institute for Global Studies. (2) Workshops or training modules will be developed for local Kalamazoo-area high school teachers to help them promote science to under-represented groups. (3) Going into the local classroom to partner with local high school teachers in the promotion of science. (4) Developing a Career Forum as part of the Introduction to Biochemistry curriculum at WMU. The Department of Chemistry at Western Michigan University (WMU) has a long-standing relationship with area high schools through several venues: the Local ACS SEED Program, the Annual High School Symposium, and the Local ACS Section Awards Program for students and teachers. A primary focus will be (1) to develop methods to disseminate career opportunities and information and (2) to break down the barriers and student misperceptions that hinder success in science.
