Granell Ortiz, Laura B.

Profile Picture

Filters

20071
Reset filters

Settings

Citations

Publication Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    Publication
    Effect of the E11 amino acid on the ligand binding in Hemoglobin I from Lucina pectinata
    (2007) Granell Ortiz, Laura B.; López Garriga, Juan; College of Arts and Sciences - Sciences; Ríos Steiner, Jorge L.; Cortés Figueroa, José E.; Department of Chemistry; Aponte, Nilda E.
    Hemoglobin I (HbI) from Lucina pectinata (clam) is a protein that binds and transports H2S to the bacteria in the clam. HbI is one of the few known hemoglobins that carries H2S, toxic gas, in its active site, which contains a GlnE7, PheB10, PheCD1 and PheE11. The stabilization of bound ligands, including H2S, appears to be dictated by the flexibility of the unusual distal heme pocket environment. Therefore, to define the role of the PheE11 on heme-ligand stability, FT-IR and kinetics studies were performed on HbI PheE11Val, PheE11Gln and PheE11Tyr using CO as ligand. The HbI PheE11Gln exhibited three stretching vibrational frequencies in the FT-IR spectrum: 1960 cm-1 (22%), 1948 cm-1 (15%), and 1939 cm-1 (64%). While, the HbI PheE11Tyr displayed vibrations located at 1962 cm-1 (34%), 1954 cm-1 (3%), and 1941 cm-1 (63%). The HbI PheE11Val showed just two vibrational peaks at 1955 cm-1 (24%) and 1942 cm-1 (76%). Each of these frequencies was assigned to different structural conformations. The higher frequencies are assigned as open conformations were no interactions occur. Whereas, lower frequencies were assigned to a closed conformation where the residues at the distal site (B10, E7, and E11) are having direct electrostatic interactions and/or hydrogen bond with the ligand. The results suggest that single site directed mutagenesis of the HbI heme pocket affect synergistically the displacement and orientation of other amino acids in the heme moiety. Also, we suggest that the PheE11 modulate the stabilization of the ligand by steric and hydrophobic interactions between the other nearby residues (GlnE7 and PheB10), and controls ligand migration in HbI.