Pro → Ala-35 Rhodobacter capsulatus cytochrome C2 shows dynamic not structural differences. A 1H and 15N NMR study

Abstract

Comparative analysis of nuclear Overhauser effects show that the time average conformation of the wild-type and mutant Pro → Ala-35 Rhodobacter capsulatus cytochrome c2 are indistinguishable. The ring resonances of Phe-51 and Tyr-53 show that their ring flip rates increase in P35A. NH proton exchange studies show that the exchange rates of the NH of Gly-34 and the NπH of His-17 increase by ≈ 102 in P35A suggesting that their respective hydrogen bonds are destabilized in this protein. However, 3 αNH. 1H and 15N chemical shift data argue that these bonds are intact. These data are compatible if the replacement of a Pro with an Ala residue forms a cavity or increases local flexibility thus re..