Kinetics of the spontaneous transient unfolding of a native protein studied with monoclonal antibodies. Monomer/dimer transition in the tryptophan-synthase beta 2 subunit.
Included in a series of monoclonal antibodies obtained after immunization with the native holo beta 2 subunit of tryptophan synthase of Escherichia coli (EC 4.2.1.20), are some that interact preferentially with a denatured state of the antigen (Friguet et al., 1984). A study of the equilibrium and kinetic characteristics of the interaction of one of these antibodies with native apo beta 2 (i.e. free of pyridoxal 5'-phosphate) and with one of its proteolytic domains is reported here. The antibody is shown to interact strongly with the isolated domain in accordance with a simple equilibrium. In the presence of native beta 2, the antibody binds exclusively to the dissociated beta-monomer. The interaction of this antibody with native apo beta 2 is used to determine the equilibrium and kinetic constants of the monomer-dimer equilibrium. The values obtained are 4.5 X 10(-8) M for the equilibrium constant and 7.9 X 10(-3) s-1 for the rate constant of the dissociation of apo beta 2 into beta-monomers.
Chaffotte
A F
AF
Unité de Biochimie des Régulations Cellulaires Institut Pasteur, Paris, France.
Goldberg
M E
ME
D000911:Antibodies, Monoclonal; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D046911:Macromolecular Substances; D011487:Protein Conformation; D014367:Tryptophan Synthase / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D046911:Macromolecular Substances; D014367:Tryptophan Synthase