Confabulating a crystal lattice for a protein model

Structure prediction has not made crystallography obsolete, but it has however made it easier — here I explore a potential trick that could be used. Under certain conditions, proteins pack in mathematically precise crystalline lattices because the lattice configuration is energetically preferable over being free in the unfriendly crystallisation solution used. Sometimes the protein will refuse to crystallise because either it is happy in solution or it would rather unfold. As a result researchers mutate surface residues to be more hydrophobic or copy the crystal packing interface ("crystal epitope") of a homologue that crystallises. A different (untested) approach could be to design the interface with ProteinMPNN or FastDesign. The catch is that one needs to make a model of the desired supercell to optimise. Here I will discuss how to make it.