Activation Energy Spectrum of a Biomolecule: Photodissociation of Carbonmonoxy Myoglobin at Low Temperatures

Abstract

Carbon monoxide bound to myoglobin can be photodissociated with high quantum yield. The subsequent rebinding can be followed optically. In the temperature range between 40 and 200 K, rebinding can be described by a function of the form ${t}_{0}$, where $n$ and $H(t)={(1+\frac{t}{{t}_{0}})}^{\ensuremath{-}n}$ are temperature-dependent parameters. This behavior can be explained by assuming the existence of an activation-energy spectrum; the form of this spectrum is determined. The energy spectrum may be due to the existence of myoglobin conformers.