Solid phase synthesis of a 42-residue fragment of staphylococcal nuclease: properties of a semisynthetic enzyme.

The polypeptide corresponding to the amino acid sequence from residue 6 through 47 in staphylococcal nuclease has been synthesized by the solid-phase method. The synthetic product closely resembles the corresponding native polypeptide in both physical and chemical properties. The synthetic peptide may be recombined with the complimentary native peptide comprising residues 49 through 149 to form an active, semisynthetic enzyme. The "functional purification" of the crude, synthetic polypeptide by affinity chromatography was found to yield a synthetic fraction of greatly enhanced specific activity. This purification was accomplished on a column of Sepharose to which the complimentary native peptide had been covalently bound.