Purification and characterization of recombinant Rev protein of human immunodeficiency virus type 1

Recombinant Rev protein of human immunodeficiency virus type 1 has been expressed in Escherichia coli and purified by ion-exchange and gel-filtration chromatography. Specific binding of the purified protein to the Rev-responsive element of the viral RNA is demonstrated. Physical characterization of the purified protein by circular dichroism and intrinsic fluorescence spectroscopy indicate that the protein preparation is suitable for structural analysis. Circular dichroism measurements show that the protein is approximately 40-45% alpha-helix. Tryptophan fluorescence measurements suggest that the single tryptophan residue is located near the surface of the protein. Gel-filtration chromatography of the protein indicates that it has an apparent molecular mass of 33,000 daltons. This suggests that the protein in solution forms a stable tetramer consisting of monomers having molecular mass of 13,000 daltons.