Tertiary Structure Characterisation by Chemical Modification and Mass Spectrometry

Tertiary Structure Characterisation by Chemical Modification and Mass Spectrometry 

Such mass spectrometric determinations of reactive sites in intact protein strac-tures by chemical modifications in proteins have been found highly useful in strac-ture—function studies of proteins [15], such as for ion-chatmel proteins (porins see Fig. 10.11). The structures of several bacterial porins have been determined by X-ray crystallography, such as the porin from Rhodobacter capsulatus (R. c.-porin) [132] which forms a trimeric complex of 16 18-stranded P-barrels. A characteristic stmc-ture element of R. c.-porin is a central constriction loop inside the P-barrel, which has been suggested as the central site determining cation/anion permeability and 

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