PROTEIN CRYSTAL-BASED NANOMATERIALS

Ganesh Iyer
Department of Chemistry, Rensselaer Polytechnic Institute, Troy, NY 12180

Protein crystallization is a form of molecular recognition and self-assembly whose study can provide insight into these phenomena. A survey was compiled of several characteristics of intermolecular contacts in the lattice of 223 protein crystal structures. The contacts observed at these interfaces were compared with the expected contacts based on mass action. The ratios of the observed by expected contacts were studied by preference association matrices and log-linear analyses to determine the various factors that contribute to the overall interactions at the crystal interface. The loglinear paramaters were used to derive contact potentials for pairwise interactions. These contact potentials have a variety of possible uses, especially in the design of crystal interfaces to give bigger and high quality crystals.

New nanomaterials will be produced by engineering specific covalent linkages into protein crystals. Strategic modifications to the surface of the protein via site-directed mutagenesis, followed by cross-linking of the crystals of these mutants along the crystallographic planes or screw axes, will give us sheets or fibers upon subsequent dissociation of the crystal. We intend to exploit this new class of nanomaterials for applications such as ultrafiltration membranes, enzyme catalyst morphologies and ultimately microelectronic devices. Two-dimensional sheets of crystalline protein offer uniform pores and greater control of surface chemistry compared to commercial membranes. They also promise the stability of three-dimensional cross-linked enzyme crystals without the same substrate and product mass-transfer resistances.