Ruiz Martínez, Carlos R.

Profile Picture

Filters

20111
Reset filters

Settings

Citations

Publication Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    Publication
    New crystallographic structures of Oxy-HbII-III and CN-HbII-III forms from Lucina pectinata
    (2011) Ruiz Martínez, Carlos R.; López Garriga, Juan; College of Arts and Sciences - Sciences; Hernández Rivera, Samuel P.; Cadilla Vázquez, Carmen L.; García Ruiz, Juan M.; Department of Chemistry; Alston, Dallas E.
    The clam Lucina pectinata is found in the sulfide-rich southwest coastal sediments of La Parguera, Puerto Rico in the Caribbean Sea. This bivalve mollusk has developed a chemoautotrophic symbiotic relation with the bacteria within it, with varying levels of interaction via intracellular and intercellular pathways in a sulfide-rich environment. One of the most interesting interaction paths with the bacteria takes place through the family of hemoproteins; hemoglobin I (HbI), hemoglobin II (HbII) and hemoglobin III (HbIII). The structures of HbI in its aquomet, sulfide, and cyanide forms, and the oxy form of HbII have been solved. However, the structure of native oxygen-reactive hemoglobins complex (HbII-III) has remained unsolved until now. The proteins complex was isolated and purified from its natural source and crystallized using the hanging drop vapor diffusion (HDVD) and capillary counterdiffusion (CCD) techniques. Oxy and cyano derivatives of the HbII-III were crystallized. The best crystals in terms of quality and size were obtained from sodium formate at pH 5 using the CCD technique in a single capillary. Crystals of the oxy and cyano HbII-III derivatives showed a ruby-red color and nonsingular prismatic shapes. They scattered X-rays to resolution limits of 2.15 and 1.75 Å, using a 0.901 and 0.886 Å synchrotron-radiation source, respectively. The crystals belonged to the tetragonal system, space group P42212, with unit-cell parameters a = b = 74.07, c = 152.07 and a = b = 74.13, c = 152.57 Å for the oxy and cyano HbII-III, respectively. The structures of the HbII-III are necessary to gain knowledge about the HbII and HbIII protein interactions versus HbII dimer to establish a precise interpretation as oxygen carrier proteins. Also the structures will produce inside into the oxygen selection mechanism to correlate the structures with the proposed protein function and properties of these hemoglobins from L. pectinata. The interest of the oxy-HbII-III protein complex and the cyano form provides us with better insight into the heme-iron oxidation-state effect to correlate with the ligand stabilization. The association constants comparisons indicate the accessibility effect in the ligand entrance for the HbII-III and HbII-II dimers. Both structural models, oxy-HbII-III (PDB id: 3TP7) and CN-HbII-III (PDB id: 3TP8), confirm the distal heme pockets residues for HbIII. The HbII-III structural arrangement findings support the hypothesis which establishes it as the native oxygen carrier in the organism.