Interaction between cytochrome [c.sub.2] and the photosynthetic reaction center from Rhodobacter sphaeroides: role of interprotein hydrogen bonds in binding and electron transfer

The mutation to Ala of reaction center (RC) residues are performed to understand the role of short-range hydrogen bond interactions at the interface between electron transfer proteins cytochrome [c.sub.2] (cyt) and the RC from Rhodobacter sphaeroides. Based on the results it is concluded that short-range hydrogen bond interactions contribute to the close packing of residues in the central contact region between the cyt and RC near Asn m187 and Tyr L162.