Lumbricus terrestris hemoglobin: A comparison of small-angle X-ray scattering and cryoelectron microscopy data
✍ Scribed by Angelika Krebs; Jean Lamy; Serge N. Vinogradov; Peter Zipper
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1998
- Tongue
- English
- Weight
- 195 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0006-3525
No coin nor oath required. For personal study only.
✦ Synopsis
The quaternary structure of Lumbricus terrestris hemoglobin was investigated by small-angle x-ray scattering (SAXS). Based on the SAXS data from several independent experiments, a three-dimensional (3D) consensus model was established to simulate the solution structure of this complex protein at low resolution (about 3 nm) and to yield the particle dimensions. The model is built up from a large number of small spheres of different weights, a result of the two-step procedure used to calculate the SAXS model. It accounts for the arrangement of 12 subunits in a hexagonal bilayer structure and for an additional central unit of cylinder-like shape. This model provides an excellent fit of the experimental scattering curve of the protein up to h Å 1 nm 01 and a nearly perfect fit of the experimental distance distribution function p(r) in the whole range. Scattering curves and p(r) functions were also calculated for low-resolution models based on 3D reconstructions obtained by cryoelectron microscopy (EM). The calculated functions of these models also provide a very good fit of the experimental scattering curve (even at h ú 1 nm 01 ) and p(r) function, if hydration is taken into account and the original model coordinates are slightly rescaled. The comparison of models reveals that both the SAXS-based and the EM-based model lead to a similar simulation of the protein structure and to similar particle dimensions. The essential differences between the models