Soluble intein fusion proteins and methods for purifying biomolecules

A fusion protein comprising an N-intein polypeptide and an N-intein solubilization partner polypeptide joined by a peptide bond, wherein the N-intein solubilization partner polypeptide has a molecular weight of less than about 15 kDa, an Aliphatic Index value less than about 60, and a Grand Average Hydropathy value less than −1, and enhances solubility of the N-intein polypeptide compared to the N-intein polypeptide expressed in the absence of the solubilization partner polypeptide;

• and maintains the catalytic activity of the N-intein polypeptide when complexed with a C-intein domain, the C-intein domain not being a part of the fusion protein.