With support from the Inorganic, Bioinorganic and Organometallic Chemistry Program Dr. John R. Pladziewicz will investigate the extent to which electron-transfer reactions of metalloproteins depend on the three-dimensional structure of the other reactant. Rates of electron transfer will be compared for metalloproteins reacting with optical isomers, i.e., molecules which contain the same atoms connected in the same way, but which differ in their three-dimensional structures so that they are non-superposable mirror images. The results of the project may help explain the exquisite selectivity exhibited by many biological electron-transfer reactions. The principal objectives of the project are to: (1) Examine a series of electron-transfer reactions between metalloproteins and chiral coordination compounds with the expectation of identifying several reactions for which stereoselective electron transfer is detectable. (2) Measure the extent of stereoselectivity in these reactions. (3) Determine the extent to which stereoselective metalloprotein-coordination compound ion pairing in the precursor complex contributes to any observed electron-transfer stereoselectivity. (4) Determine the extent to which donor-acceptor distance and orientaion play a role in observed stereoselectivity. (5) Develop models based on available x-ray crystallographic data and observed selectivity to advance understanding of the stereochemical control of biological electron transfer.
