Initial biophysical characterization of Amynthas gracilis giant extracellular hemoglobin (HbAg)
- PDF / 934,529 Bytes
- 12 Pages / 595.276 x 790.866 pts Page_size
- 44 Downloads / 166 Views
ORIGINAL ARTICLE
Initial biophysical characterization of Amynthas gracilis giant extracellular hemoglobin (HbAg) J. B. S. Oliveira1,2 · L. Ramos1,2 · C. O. Souza1,2 · I. Sebastião1,2 · C. Caruso1 · F. A. O. Carvalho3 · J. W. P. Carvalho4 · P. G. Morgante1 · P. S. Santiago1 Received: 10 February 2020 / Revised: 1 August 2020 / Accepted: 11 August 2020 © European Biophysical Societies’ Association 2020
Abstract The aim of the present work was the biophysical characterization of the Amynthas gracilis hemoglobin (HbAg). The oxyHbAg optical absorption data, with Soret and Q bands centered at 415, 540 and 575 nm, were stable and unchanged at pH 7.0. An increase in pH promotes decrease in the intensity in the optical absorption bands, suggesting an oligomeric dissociation and partial oxidation. Identical stability at pH 7.0 was observed in DLS results that presented a hydrodynamic diameter of 28 nm, characteristic of the whole oligomer. DLS shows that HbAg undergoes oligomeric dissociation and an aggregation/denaturation process that corroborates spectroscopic data. Our results showed that the monomer d presents four isoforms with molecular mass (MM) ranging from 16,244 to 16,855 Da; the trimer subunit presents two isoforms, (abc) 1 and (abc)2, with MM of 51,415 ± 20 Da and 51,610 ± 14 Da, respectively, and a less intense species, at 67,793 Da, assigned to the tetramer abcd. Monomeric chains a, obtained from reduction of the disulfide-bonded trimer abc, present four isoforms with MM 17,015 Da, 17,061 Da, 17,138 Da and 17,259 Da. DLS and LSI revealed an isoeletric point (pI) of oxy-HbAg of 6.0 ± 0.3 and 5.5, respectively. Data analysis by IEF–SDS–PAGE revealed that the pI of oxy-HbAg is 6.11, correlating with DLS and LSI data. These studies indicate that oxy-HbAg is very stable, at pH 7.0, and has differing properties from orthologous giant hemoglobins. Keywords Oligomeric stability · Spectroscopy studies · Erythrocruorin · Hemoprotein · Biophysical characterization
Introduction Hemoglobins (Hb) are biomolecules responsible for oxygen transportation. Human beings have hemoglobin (Hb) with molecular mass (MM) of 64 kDa, four polypeptide chains Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00249-020-01455-8) contains supplementary material, which is available to authorized users. * P. S. Santiago [email protected] 1
São Paulo State University (Unesp), Campus of Registro, Registro, SP, Brazil
2
Institute of Chemistry, São Paulo State University (Unesp), Araraquara, SP, Brazil
3
Federal University of South and Southeast Pará (Unifesspa), Marabá, PA, Brazil
4
State University of Mato Grosso, Barra do Bugres, MT, Brazil
containing a single heme group for each one, high tendency to oligomeric dissociation at diluted solutions, and found inside red blood cells (Voet and Voet 2010). However, this type of oxygen carrier is not present in all organisms in nature. Annelids, mollusks, and arthropods have other types of Hb, known as erythrocruorins (Ec),
Data Loading...
