A gentle vapor-diffusion technique for cross-linking of protein crystals for cryocrystallography

Protein crystals have been cross-linked by a gentle technique whereby glutaraldehyde is introduced by vapor diffusion into the crystallization droplet containing the crystals. Diffraction analyses of crystals of three different proteins show that cross-linking prevents, in a large part, the lattice disorder normally observed on rapid cooling of these crystals. The diffraction results suggest that this cross-linking procedure, performed as a simple extension of the standard vapor-diffusion crystallization experiment, may generally aid in the cooling of fragile protein crystals for which standard procedures of cryopreservation prove inadequate.