MULTINUCLEAR NMR-STUDY OF THE STRUCTURE OF THE FV FRAGMENT OF ANTIDANSYL MOUSE IGG2A ANTIBODY

A multinuclear NMR study is reported of Fv, which is a minimum antigen-binding unit of immunoglobulin. Fv has been prepared by clostripain digestion of a mouse anti-dansyl IgG2a monoclonal antibody that lacks the entire C(H)1 domain [Takahashi, H., Igarashi, T., Shimada, I., & Arata, Y. (1991) Biochemistry 30, 2840-2847). A variety of Fv analogues labeled with H-2 in the aromatic rings and with C-13 and/or N-15 in the peptide bonds have been prepared and used for multinuclear NMR analyses of Fv in the absence and presence of epsilon-dansyl-L-lysine (DNS-Lys). It has been shown that H-1-N-15 shift correlation spectra of Fv sensitively reflect the antigen binding and can be used along with H-1 and C-13 spectral data for the structural analyses of antigen-antibody interactions. Hydrogen-deuterium exchange of the amide protons has been followed in the absence and presence of DNS-Lys by using the H-1-N-15 shift correlation spectra. Use of the beta-shift observed for the carbonyl carbon resonances has also been helpful in following the hydrogen-deuterium exchange. On the basis of the NMR data obtained, the static and dynamic structure of the Fv fragment in the absence and presence of DNS-Lys has been discussed.