Metalloprotein donor-acceptor distances

Table III summarizes rate, helicity, and donor-acceptor distance data for the 16-mer bundle. Because of the observable trend in conformation versus rate in the electron transfer studies, it was decided to measure donor-acceptor distances in the 16-mer metalloprotein bundles. In order to study the effects of solution conditions on H, the donor-acceptor distance, Forster energy transfer was used as a spectroscopic ruler, according to...

Work on intramolecular ET complexes has included investigations of intervalence spectra in binuclear complexes (29,160,178). Recent research has been focused on measurements of the distance and driving force dependence of intramolecular ET rates in donor-acceptor complexes. Concurrently, methods to monitor ET in metalloproteins and protein-protein complexes have been developed. Our aim in this chapter is to compare and contrast ET data from proteins and donor-acceptor complexes in an attempt accurately to represent the current level of understanding of ET processes as they relate to biological systems. Our emphasis will be on the potential control of ET by variation in fundamental parameters such as the ET distance, driving force, and intervening medium. 

The study of electron transfer (ET) in metalloproteins has taken advantage of the foundation laid by research on simple chemical systems (173,174,189). It was recognized early that parameters such as ET distance and driving force would have to be carefully controlled in order to provide experimental information that could be used in a meaningful way to evaluate theoretical models (108-110). Since it proved to be difficult to accomplish this goal through intermolecular ET studies, attention turned to measurements of intramolecular ET rates in systems in which the donor and acceptor are separated by a fixed and known distance. 

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