The protein could be a dimer, a tetramer, or a hexamer in the unit cell of the crystal, I wonder what is the known maximum number of polymers in the asymmetric unit, it doesn't have to be homodimer, homotetramer or homohexamer if you know what I mean. Thanks.
If you look at the Highlights page at PDBe,
http://www.ebi.ac.uk/pdbe/PDBhighlights.html
The maximum number of chains in an X-ray structure (and conventionally the ASU is deposited) is 360
If your crystal diffracts enough to get the cell parameters, you can get an estimate of the number of monomers of your protein that are likely present in the asymmetric unit by making a Matthews coefficient analysis (with your cell parameters and the molar mass of your protein as input). This is present in ccp4.
Yes, it is awesome to me - as Matthew noted the structure of Panicum Mosaic Virus (PMV) has pseudo symmetry F23; crystallographic unit cell space group P2(1) with a=411.7Å, b=403.9Å and c=412.5Å, with β=89.7°, and the asymmetric unit was two entire T=3 virus particles, or 360 protein subunits. See http://www.rcsb.org/pdb/explore/explore.do?structureId=4V99
A buddy of mine in graduate school published 3RG2 which contains 10 molecules in the asu. Each of the molecules was slightly different than the rest complicating NCS.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3292774/
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