THE STRUCTURE OF PORIN FROM PARACOCCUS-DENITRIFICANS AT 3.1-ANGSTROM RESOLUTION

The crystal structure of a non-specific porin from Paracoccus denitrif icans at 3.1 Angstrom resolution has been solved by molecular replacem ent using the porin from Rhodopseudomonas blastica as the search model . Paracoccus porin is very similar to other non-specific porins of kno wn structure: a trimer of 16 stranded beta-barrels each with a central pore constricted by a long extracellular loop folding back against th e barrel wall. The distinctive distribution of charged residues of thi s non-specific porin contributes to understanding the relation between structure and ion selectivity. (C) 1997 Federation of European Bioche mical Societies.