What are some useful physical information of a protein?
All the information about a protein, biochemical or functional is encoded in its structure, which are primary (Amino Acid (AA) sequence), secondary (alpha helix or beta pleated sheet), tertiary (overall 3D structure of a single peptide) and quaternary (overall 3D-structure of a protein composed of multiple peptides which are attached together through various different bonds) structures (http://en.wikipedia.org/wiki/Protein_structure). 

Obviously, the key determinants for all these structures is the AA sequence of a protein, since that determines the biochemical property of a protein as well as its function (e.g. enzymatic residues and active sites, functional domains, motifs, whether it is post-translationally modified or not by phosphorylation and whether that causes its activation or inactivation through conformational changes or its interaction with other proteins etc).