Crystals of an antibody F V fragment against an integral membrane protein diffracting to 1.28 Å resolution

The F v fragment of a monoclonal antibody, 7E2 (IgG 1 , κ, murine), which is directed against the integral membrane protein cytochrome c oxidase (EC 1.9.3.1) from Paracoccus denitrificans , was cloned and produced in Escherichia coli . Crystals suitable for highresolution X‐ray analysis were obtained by microdialysis under low salt conditions. The crystals belong to the orthorhombic space group P2 1 2 1 2 1 with unit cell dimensions of a = 51.51 Å, b = 56.15 Å, c = 99.86 Å (1 Å = 0.1 nm) and contain one F v fragment per asymmetric unit. Using synchrotron radiation diffraction data were collected up to 1.28 Å resolution. This high resolution is very unusual for a heterodimeric protein. The crystals should open the way for refining not only the atomic positions, but also for obtaining information about internal dynamics. © 1995 Wiley‐Liss, Inc.