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Oral Sessions
Day 4, June 25（Wed.） 12:10-12:25
Room A (Maesato West)
- 4A-O1-1210
Understanding the Binding and Structures of Model Complexes of Polypeptides and Cofactors: Insights into structural enzymology of radical proteins
(1U of Hong Kong, 2Shandong Public Health Clinical Center)
oIvan Chu1,2
Competitive interactions between metal cofactors and the functional groups of polypeptides give rise to a diverse range of structures and chemical behaviors in metalloproteins that control cellular activity and structural enzymology of radical proteins. For example, radical-mediated protein tyrosine nitration is a hallmark of nitrative stress, recognized as a ubiquitous pathological process in every major human disease. Tyrosine nitration is a highly site-specific reaction, regioselectively targeting a single tyrosine residue among the many tyrosyl residues within a protein. In this study, we investigate key aspects of this competitive binding using a family of ternary systems composed of metal ions, auxiliary ligands, and peptides. Structural diversity was analyzed and validated through tandem mass spectrometry, both with and without peptide derivatization and substitution, as well as density functional theory calculations and infrared multiple-photon dissociation spectroscopy. Despite the apparent complexity of these binding interactions, the chemistry can be simply described using the simple acid-base chemistry. The resulting structures were experimentally examined in accordance with theoretical predictions. Energy minimization in these complexes follows multiple pathways involving various functional groups, leading to a rich and diverse chemistry.