APPLICATIONS OF ELECTROSPRAY MASS-SPECTROMETRY TO STUDIES ON THE STRUCTURAL-PROPERTIES OF RIBONUCLEASE-A AND RIBONUCLEASE-B

Deuterium-exchange experiments were performed on ribonuclease A (RNase A) and its glycosylated form, ribonuclease B (RNase B), using electro spray ionization mass spectrometry. The number of exchangeable protons was found to be similar for both forms of the enzyme, indicating that the oligosaccharide moiety on RNase B does not exert any influence on protein conformation. Four main glycoform populations were identified in RNase B, each of which was homogeneous and associated with one pho sphate group. Spectra for RNase A were heterogeneous due to the presen ce of 0-3 phosphate groups bound to the enzyme.