I suggest looking at interpro site (enter link description here) to get detailed information about protein domains
A popular tool for prediction of affinity should be FIMO, part of the MEME suite (http://meme.sdsc.edu):
Timothy L. Bailey, Mikael Bodén, Fabian A. Buske, Martin Frith, Charles E. Grant, Luca Clementi, Jingyuan Ren, Wilfred W. Li, William S. Noble, "MEME SUITE: tools for motif discovery and searching", Nucleic Acids Research, 37:W202-W208, 2009.
I found interesting suggestions also here:
A Linear Model for Transcription Factor Binding Affinity Prediction in Protein Binding Microarrays Annala M, Laurila K, Lähdesmäki H, Nykter M (2011) A Linear Model for Transcription Factor Binding Affinity Prediction in Protein Binding Microarrays. PLoS ONE 6(5): e20059. doi:10.1371/journal.pone.0020059
p.s. look also at past answers in the site