On the role of Tyr 34L in the antibody combining site of the dinitrophenyl binding protein 315

Autor: Raymond A. Dwek, Rina Zakut, Moshe Gavish, David Givol, Y. Ben Neriah, W.R.C. Jackson
Rok vydání: 1979
Předmět:
Zdroj: Molecular Immunology. 16:957-963
ISSN: 0161-5890
DOI: 10.1016/0161-5890(79)90097-x
Popis: The role of Tyr 34L in the combining site of the dinitrophenyl binding mouse myeloma protein 315 has been studied by chemical modification. Tyr 34L was specifically nitrated by separating the peptide chains of the Fv fragment intoVL and VH (Hochman et al., 1973), nitrating VL with tetranitromethane and reassociating the modified VL with unmodified VH Comparison of the binding properties of NO2 Fv and Fv, and of NO2VL and VL was performed by equilibrium dialysis with 3H-Dnp-lysine, dinitrophenol, Tnpamino caproic acid and Tnp-amino ethylamine at pH 5.0 and pH 8.0. Since the pKa of the NO2 Tyr in the above fragments is 6.2–6.6. these binding studies were designed to investigate the possibility of a steric effect of introduction of the nitro group, and to demonstrate the presence or absence of a hydrogen bond between Tyr 34L and the ligand suggested in a recent paper (Dower et al., 1977), by observing the effect of ionization of the phenol group. Both the affinities and numbers of sites of the modified and unmodified fragments were found to be very similar. Nuclear magnetic resonance studies showed that the hapten occupied the same position in the combining sites of the modified and unmodified Fv fragments. Hence it is concluded that Tyr 34L does not form a hydrogen bond to nitrophenyl ligands.
Databáze: OpenAIRE