Formation and properties of S‐protein complex with S‐peptide‐containing fusion protein

Abstract
A fusion protein (FP) comprised of the RNase A S‐peptide and human epidermal growth factor was shown to form a stable noncovalent catalytically active complex with the RNase A S‐protein at a stoichiometric ratio 1:1 with K diss = 5.0 × 10−7M. The S‐protein complex with FP exhibits the pyrimidine specificity toward substrates in both reactions catalyzed by RNase S, transesterification and hydrolysis. The fusion protein can be determined specifically and quantitatively in the presence of S‐protein by RNase activity assays. The possibility of effective purification of S‐peptide‐containing proteins by affinity chromatography on an S‐protein‐Sepharose column has been demonstrated.