Application of 13C nuclear magnetic resonance spectroscopy to molecular structural analyses of antibody molecules.

A 13C nuclear magnetic resonance study of a mouse anti-dansyl monoclonal antibody is reported. The antibody molecule was specifically labeled with [1-13C]methionine by growing hybridoma cells in serum-free medium. It was possible to observe all the carbonyl carbon resonances of the antibody. Fab and Fc fragments have been obtained from the antibody and used successfully for the assignment of each of the carbonyl resonances to either the Fab or Fc region. It has been shown that the spectrum of the intact antibody is simply those of Fab and Fc superimposed. It has also been shown that site specific assignments of carbonyl resonances can be made by means of a double labeling technique developed by Kainosho and coworkers.