Protein crystallographers are well aware of the trap crystallizing E. coli proteins instead macromolecule interest if heterologous recombinant protein expression in was part experimental pipeline. Among well-known culprits YodA metal-binding lipocalin (25 kDa) and YadF carbonic anhydrase (a tetramer 25 kDa subunits). We report a novel crystal form another such culprit, HPII catalase, which is t...