9627773 Lopez-Garriga The goal of this project is to investigate the molecular basis for oxidation-reduction and ligand selection process of hemoglobin, (Hb1) isolated from Lucina pectinata. This hemoglobin, produced by a symbiotic interaction between the clam and a bacteria, transports H2S to the bacteria and binds O2. Dr. Lopez-Garriga will examine how reduction/oxidation of the metal center affects the porphyrin ring, and the ligand interaction with nearby amino acids. Regarding this, the ligand binding properties of Hb 1 may be influenced by the low distal pocket polarity resulting from the array of phenylalanyl residues surrounding the heme. Studies on monomeric hemoglobins, such as Hb 1, with extreme hydrophobic heme pocket environments can provide useful models for heme proteins to answer questions such as: How does ligand selection occur? Which ligand-protein conformational and structural changes are important? What controls ligand reactivity in these proteins? How do the heme pocket aromatic residues contribute or modulate the association and dissociation ligand rate constants? To answer these questions, Resonance Raman, FTIR, Time-Resolved Infrared Spectroscopy and Vibrational Analysis studies of Hb1 and ligand complexes (i.e. H2S, O2 and CO) are planned in order to probe the relation between the active site structure, oxidation-reduction reactions, Hb1 conformation, and the function of the protein. %%%
