Recombination dynamics in a hemispherical cage. A model of geminate ligand binding in the hemeprotein pocket

✍ Scribed by N.J. Cotes; Mark G. Sceats

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 512 KB
• Volume: 141
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(87)85049-2

✦ Synopsis

A simple model of recombination in a hemispherical pocket is developed in which the only parameters are the long-range attractive potential, which leads to binding, and the size of the pocket. A transition state appears when the problem is contracted from three dimensions to a one-dimensional problem in the binding coordinate R. The rate of passage over the barrier is evaluated in the transition state limit to give an upper bound to recombination rate. The temperature dependence ofthe rate is in agreement with that observed in protoheme, indicating that the model correctly incorporates configurational contributions. For oxyhemoglobin the deviation in the magnitude of the rate is attributed to an entropy of activation due to ligand orientation.