A Metal Organic Framework with Spherical Protein Nodes: Rational Chemical Design of 3D Protein Crystals

We
describe here the construction of a three-dimensional, porous,
crystalline framework formed by spherical protein nodes that assemble
into a prescribed lattice arrangement through metal–organic
linker-directed interactions. The octahedral iron storage enzyme,
ferritin, was engineered in its C3 symmetric
pores with tripodal Zn coordination sites. Dynamic light scattering
and crystallographic studies established that this Zn-ferritin construct
could robustly self-assemble into the desired bcc-type crystals upon
coordination of a ditopic linker bearing hydroxamic acid functional
groups. This system represents the first example of a ternary protein–metal–organic
crystalline framework whose formation is fully dependent on each of
its three components.