Using the newly available refined co-ordinates of deoxy and oxyhaemoglobin, we have reexamined and compared the interfaces between the dimers α1β1 and α2β2. The most extensive monomer-monomer contacts are between α1 and β2, and, symmetrically, α2 and β1. In oxyhaemoglobin these interfaces bury 700 Å2less protein surface than in deoxyhaemoglobin. The α1α2 interface involves similar salt bridges in both forms, but in oxyhaemoglobin buries 240 Å2more surface than in deoxyhaemoglobin. There is a loosely packed β1β2 interface burying 320 Å2 of surface in oxyhaemoglobin; there is no β1β2 interface in deoxyhaemoglobin. The greater stability of the deoxy form, in the absence of ligands, can be attributed to a combination of hydrophobic, van der Waals' and electrostatic interactions.
All Science Journal Classification (ASJC) codes
- Structural Biology
- Molecular Biology