On the structure of crystalline ribulosebisphosphate carboxylase from Alcaligenes eutrophus

Ribulosebisphosphate carboxylase from the hydrogen bacterium Alcaligenes eutrophus having a molecular weight of 534000 and consisting of eight large and eight small subunits has been crystallized by microdialysis using inorganic as well as organic precipitating agents. Crystals have tetragonal space group P42212, a = b = 11.27 nm, c = 20.14 nm, and contain one quarter molecule per asymmetric unit. X-rays are diffracted to 0.35-nm resolution on still photographs. Light optical diffractions of electron micrographs of thin sectioned crystals displayed patterns which could be interpreted on the basis of the unit cell determined by X-rays. Packing considerations are in accord with our earlier proposal regarding the subunit arrangement of this enzyme which differs from that reported for tobacco ribulosebisphosphate carboxylase.