IDENTIFICATION OF HUMAN NONPANCREATIC-TYPE RIBONUCLEASE BY ANTIBODIESOBTAINED AGAINST A SYNTHETIC PEPTIDE

An antibody that recognizes human nonpancreatic-type ribonuclease was obtained by immunizing a rabbit with a 14-residue synthetic peptide co rresponding to the N-terminal sequence of eosinophil-derived neurotoxi n which is identical to human liver ribonuclease. This amino acid sequ ence is unique to this protein. The anti N-peptide antibody was purifi ed by protein A-Sepharose and by using ELISA and SDS-PAGE immunoblot t echniques, the antibody reactivity against EDN and partially purified nonpancreatic-type ribonucleases from human plasma and urine was obser ved. Cross-reactivity with bovine pancreatic ribonuclease A and other proteins was not detected. In addition, the activity of the nonpancrea tic-type ribonuclease was not affected by the antibody. The immune res ponse was elicited without the need for a carrier protein showing that the N-terminal sequence of nonpancreatic ribonuclease contains a spec ific epitope. This antibody can be used for the immunological identifi cation of both the native and denatured forms of this type of enzyme.