[Bio-software] Identifying proteins form amino acid composition

[Astala Vista]

I have discovered a couple of independently published papers that 
describe the amino acid composition of a protein that is of interest to 
me. The approximate length of the protein is known in both cases and the 
pI has been determined in one case. I'd like to identify the protein 
from the composition data.

I'm aware of the AACompIdent program available at Expasy 
(http://www.expasy.ch/tools/aacomp/), but I'm not convinced that it's 
doing exactly what I want. As far as I can tell, AACompIdent does not 
allow for the possibility that the protein whose composition you know 
might be derived from a larger protein by post-translational cleavage. 
What I'd like to do is a search similar to that carried out by 
AACompIdent, but using a sliding window whose size is set by the user.

Any ideas?

Thanks.