ARPwARP 7.4 for Mac can be downloaded from our website for free. The actual developer of this free software for Mac is European Molecular Biology Laboratory. The most popular version among the program users is 7.4. The software is categorized as Education Tools.
From the developer:
ARP/wARP is a crystallographic macromolecular model building application. ARP/wARP combines pattern recognition-based interpretation of an electron density, its modelling as a hybrid model and a maximum likelihood pa- rameter refinement with REFMAC. You can build proteins, RNA/DNA, secondary structure, side chains, loops, solvent and ligands.
You may want to check out more software for Mac, such as Trapcode Particular, iRNAi or Solar Eclipse Maestro, which might be similar to ARPwARP.