Homodimeric and expanded behaviour of trimethylamine dehydrogenase in solution at different temperatures |
| |
Authors: | Helmut Cölfen Stephen E. Harding Emma K. Wilson Len C. Packman Nigel S. Scrutton |
| |
Affiliation: | (1) National Centre for Macromolecular Hydrodynamics, University of Nottingham, LE12 5RD Sutton Bonington, UK;(2) Centre for Molecular Recognition, Department of Biochemistry, University of Cambridge, Tennis Court Road, CB2 1QW Cambridge, UK;(3) Present address: Colloid Chemistry Department, Max-Planck-Institute for Colloid and Interface Research, Kantstrasse 55, D-14513 Teltow, Germany |
| |
Abstract: | Earlier studies using x-ray crystallography have shown that trimethylamine dehydrogenase (TMADH) from methylotropic bacteria exists as homodimers in the crystalline state. In this present hydrodynamic study we show that this is true also in dilute solution conditions and investigate the degree of swelling or relaxation of the protein in solution. Analytical ultracentrifugation was used to determine the molar mass and to investigate whether the homodimeric nature of this molecule in crystal form — as visualized by x-ray crystallography — is reproduced in dilute solution at temperatures between 4 and 40°C. The globular solution structure determined at 4 and 40°C is in good agreement with crystallographic data although trimethylamine dehydrogenase was found to be either more asymmetric in solution — or highly hydrated —, a phenomenon found to increase with temperature. In agreement with the crystallographic structure, the enzyme sediments as a homodimer with a molar mass of (163,000±5,000) g/mol. The concentration dependence of the sedimentation coefficient in the range of 0–1 mg/ml, indicates that no association or dissociation occurs. These findings are additionally supported by sedimentation equilibrium data in the concentration range of 0 to 1.8 mg/ml. Finally, from the sedimentation coefficient distribution at various temperatures, it was concluded that the enzyme is conformationally flexible and assumes an even more expanded structure at higher temperatures which is in good agreement with the hydrodynamic calculations performed.Correspondence to: S. E. Harding |
| |
Keywords: | Trimethylamine dehydrogenase Analytical ultracentrifugation Hydrodynamics Homodimers |
本文献已被 SpringerLink 等数据库收录! |
|