STRUCTURE DETERMINATION AND REFINEMENT OF RIBULOSE 1,5-BISPHOSPHATE CARBOXYLASE OXYGENASE FROM SYNECHOCOCCUS PCC6301/

The structure of an activated quaternary complex of ribulose 1,5-bisph osphate carboxylase/oxygenase (rubisco) from Synechococcus PCC6301 has been solved by molecular replacement. The protein crystallizes in an orthorhombic P2(1)2(1)2(1) unit cell with a complete L(8)S(8) complex consisting of 4608 residues (37 680 non-hydrogen atoms) in the asymmet ric unit. Data were collected both on film and image plate using synch rotron radiation; there were 218 276 unique reflections in the final 2 .2 Angstrom data set. The eightfold non-crystallographic symmetry coul d be used both to improve map quality and to reduce the computing requ irements of refinement. The coordinates were refined using strict non- crystallographic symmetry constraints. The stereochemistry of the fina l model is good, and the model has an R value of 20.0% for the reflect ions between 7 and 2.2 Angstrom.