Tunneling in Ligand Binding to Heme Proteins
Abstract
Rebinding of carbon monoxide to the beta chain of hemoglobin after photodissociation by a laser flash is intramolecular below about 200 K. Above 25 K, rebinding occurs via classical over-the-barrier motion; below, quantum-mechanical tunneling dominates. Both are described by an energy spectrum peaked at Epeak = 4.0 kilojoules per mole. The barrier width d(E), determined from the energy dependence of the tunneling rate, depends on barrier height, d(E) ≈ 0.05 nanometer × (E/Epeak)1.5.
- Publication:
-
Science
- Pub Date:
- June 1976
- DOI:
- 10.1126/science.1273579
- Bibcode:
- 1976Sci...192.1002A