The binding of Tnp (2,4,6-trinitrophenyl) derivatives to the Fv fragment (variable region of heavy and light chains) of the mouse myeloma IgA protein MOPC 315 was investigated by 270MHz proton nuclear magnetic resonance. Two of the haptens, Tnp-glycine and Tnp-l-aspartate, are in fast exchange with the Fv fragment, and the changes in chemical shifts for both protein and hapten resonances were determined by titrations. For the tightly binding hapten ε-N-Tnp-α-N-acetyl-l-lysine, which is in slow exchange with the Fv fragment, the changes in chemical shifts for the hapten H3+H5 resonances were determined by cross-saturation. By using these data and the known structure of the combining site of protein MOPC 315 [Dwek, Wain-Hobson, Dower, Gettins, Sutton, Perkins & Givol (1977), Nature (London) 266, 31–37] the mode of binding of Tnp derivatives is deduced by ring-current calculations. The trinitrophenyl ring stacks with tryptophan-93L (light chain) in the ‘aromatic box’ formed by tryptophan-93L, tyrosine-34L and phenyl-alanine-34H (heavy chain). Further evidence for the stacking interaction with a tryptophan residue is provided by the similarity of the optical-difference spectra observed with Tnp-aminomethylphosphonate in the presence of either the Fab fragment (light chain and N-terminal half of heavy chain) of protein MOPC 315 or tryptophan. These data show that the modes of binding of all the Tnp derivatives are very similar, despite a 100-fold range in their affinities. It is also concluded that the modes of binding of Dnp (2,4-dinitrophenyl) and Tnp derivatives to protein MOPC 315 are very similar, and that the structural basis for this is that the aromatic box is large enought to allow the trinitrophenyl ring to stack with tryptophan-93L while still forming hydrogen bonds to asparagine-36L and tyrosine-34L.
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January 1978
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Research Article|
January 01 1978
The binding of 2,4,6-trinitrophenyl derivatives to the mouse myeloma immunoglobulin A protein MOPC 315
Steven K. Dower;
Steven K. Dower
1Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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Peter Gettins;
Peter Gettins
2Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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Roland Jackson;
Roland Jackson
3Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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Raymond A. Dwek;
Raymond A. Dwek
4Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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David Givol
David Givol
5Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1978 London: The Biochemical Society
1978
Biochem J (1978) 169 (1): 179–188.
Citation
Steven K. Dower, Peter Gettins, Roland Jackson, Raymond A. Dwek, David Givol; The binding of 2,4,6-trinitrophenyl derivatives to the mouse myeloma immunoglobulin A protein MOPC 315. Biochem J 1 January 1978; 169 (1): 179–188. doi: https://doi.org/10.1042/bj1690179
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