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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Molecular masses and sedimentation coefficients of extracellular hemoglobin of Glossoscolex paulistus: Alkaline oligomeric dissociation

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Author(s):
Carvalho, Francisco Adriano O. [1] ; Santiago, Patricia S. [1] ; Borges, Julio C. [1] ; Tabak, Marcel [1]
Total Authors: 4
Affiliation:
[1] Univ Sao Paulo, Inst Quim Sao Carlos, Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: International Journal of Biological Macromolecules; v. 48, n. 1, p. 183-193, JAN 1 2011.
Web of Science Citations: 18
Abstract

The giant extracellular hemoglobin of Glossoscolex paulistus (HbGp) has a molecular mass (M) of 3600 +/- 100 kDa and a standard sedimentation coefficient (s(20.w)(0)) of 58 S. estimated by analytical ultracentrifugation (AUC). In the present work, further AUC studies were developed for HbGp, at pH 10.0, which favors oligomeric dissociation into lower M species. The HbGp oligomer is formed by globin chains a, b, c and d plus the linker chains. The pure monomeric fraction, subunit d, and HbGp at pH 10.0, in the presence of beta-mercaptoethanol, were also studied. Our results indicate that for samples of pure subunit d, besides the monomeric species with s(20.w)(0) of 2.0 S, formation of dimer of subunit d is observed with s(20.w)(0) of around 2.9 S. For the whole HbGp at pH 10.0 contributions from monomers, trimers and linkers are observed. No contribution from 58 S species was observed for the sample of oxy-HbGp at pH 10.0, showing its complete dissociation. For cyanomet-HbGp form a contribution of 17% is observed for the un-dissociated oligomer, consistent with data from other techniques that show the cyanomet-form is more stable as compared to oxy-HbGp. Masses of HbGp subunits, especially trimer abc and monomeric chains a, b, c and d, were also estimated from sedimentation equilibrium data, and are in agreement with the results from MALDI-TOF-MS. (C) 2010 Elsevier B.V. All rights reserved. (AU)