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Small angle x‐ray scattering of the hemoglobin from Biomphalaria glabrata
Author(s) -
Arndt Márcio H. L.,
Oliveira Cristiano L. P. de,
Régis Wiliam C. B.,
Torriani Iris L.,
Santoro Marcelo M.
Publication year - 2003
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.10367
Subject(s) - small angle x ray scattering , chemistry , radius of gyration , crystallography , scattering , biomphalaria glabrata , gyration , hemoglobin , molecular physics , geometry , polymer , physics , optics , biochemistry , mathematics , organic chemistry , zoology , schistosoma mansoni , biology , helminths , schistosomiasis
The hemoglobin from Biomphalaria glabrata is an extracellular respiratory protein of high molecular mass composed by subunits of 360 kDa, each one containing two 180 kDa chains linked by disulfide bridges. In this work, small angle x‐ray scattering (SAXS) measurements were performed with the hemoglobin at pH 5.0 and 7.5. Radii of gyration of 98.6 ± 0.5 and 101.8 ± 0.2 Å and maximum diameters of 300 ± 10 and 305 ± 10 Å, respectively, were obtained from Guinier plot extrapolation and analytical curve fitting. The pair distance distribution functions p(r) corresponded to globular particles with a somewhat anisotropic shape for both preparations. Computer analysis of the low angle part of the scattering curve led to the determination of the low resolution envelope of the protein, revealing a P 222 symmetry. Shape reconstruction from ab initio calculations using the complete scattering curve furnished a compact prolate three‐dimensional (3D) bead model for the protein. Hydrodynamic parameters were obtained from experiments and theoretical calculations using the 3D model. The results of the structural and biochemical studies reported herein indicate that the multisubunit structure of this hemoglobin is compatible with a tetrameric arrangement. © 2003 Wiley Periodicals, Inc. Biopolymers 69: 470–479, 2003