Model of Thioredoxin from Escherichia coli based on the Protein Data Bank entry 2TRX:
http://www.rcsb.org/pdb/explore/explore.do?structureId=2trx

STL file created using VMD:
http://www.ks.uiuc.edu/Research/vmd/

The protein backbone is represented in "cartoon" form. The reactive cysteine residues are represented as spheres.

Successfully printed by a Replicator 2 in PLA using MakerWare(TM) 2.2.2.89, standard resolution (3 shells, 25% infill), with raft and supports.