REDUCTION IN THE AMIDE HYDROGEN-EXCHANGE RATES OF AN ANTILYSOZYME FV FRAGMENT DUE TO FORMATION OF THE FV-LYSOZYME COMPLEX

The Fv fragment of the monoclonal antibody D1.3 was expressed in bacte ria. Standard triple resonance techniques were used to obtain the NMR resonance assignments for 211 out of 215 backbone N-15/NH atoms for D1 .3 Fv. Using these assignments, hydrogen exchange rates are measured f or 82 amide hydrogen atoms in D1.3 Fv free and bound to hen eggwhite l ysozyme. Upon binding to antigen, exchange rates are decreased for res idues throughout the Fv. Many of these residues are located remote fro m the site of interaction with the antigen. These changes are larger t han previously observed for the antigen portion of the complex. Eviden tly, the beta-sheet structure of the Fv propagates the effects of bind ing more efficiently than the antigen. These effects are compared betw een the three different polypeptide chains that make up the complex. T hese data suggest that reduced dynamics are a general feature of antib ody binding to antigen. (C) 1997 Academic Press Limited.