Crystals of an antibody Fv fragment against an integral membrane protein diffracting to 1.28 A resolution.

The Fv fragment of a monoclonal antibody, 7E2 (IgG1, kappa, 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 high-resolution 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 A, b = 56.15 A, c = 99.86 A (1 A = 0.1 nm) and contain one Fv fragment per asymmetric unit. Using synchrotron radiation diffraction data were collected up to 1.28 A 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.