Immunochemical evidence for conformational flexibility and its modulation by specific ligands in the .beta.2 subunit of Escherichia coli tryptophan synthase
- 1 May 1983
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 22 (11), 2708-2714
- https://doi.org/10.1021/bi00280a019
Abstract
The immunochemical reactivity of unfractionated antibodies elicited by denatured .beta.2 subunits of E. coli tryptophan synthase [L-serine hydro-lyase (adding indole) EC 4.2.1.20] with the homologous antigen and with the native enzyme is examined. These antibodies recognize the native apoenzyme nearly and the denatured protein. After binding of its cofactor, pyridoxal 5''-phosphate, the protein exhibits a much lower immunoreactivity toward these antibodies. This decrease of affinity becomes even more pronounced when the .beta.2 protein interacts with the .alpha. subunit. Reduction of the Schiff base formed between the cofactor and the protein leads to a strong decrease of immunoreactivity. To account for these results, it is proposed that apo-.beta.2 must be a dynamic flexible structure that easily exposes to the solvent regions of its polypeptide chain that normally are buried in its interior. The increase in rigidity of this structure upon binding of the cofactor, reduction of Schiff base and formation of the .alpha.2.beta.2 complex would then account for the decreased immunoreactivity of these various states of the native .beta.2 protein.This publication has 22 references indexed in Scilit:
- Detection of the homology among proteins by immunochemical cross-reactivity between denatured antigens. Application to the threonine and methionine regulated aspartokinases-homoserine dehydrogenases from Escherichia coli K 12Biochemistry, 1978
- Immunochemical analysis of the conformational properties of intermediates trapped in the folding and unfolding of bovine pancreatic trypsin inhibitorJournal of Molecular Biology, 1978
- Isolation and characterization of independently folding regions of the β chain of Escherichia coli tryptophan synthetaseBiochemistry, 1977
- Preparation and characterization of a modified form of beta2 subunit of Escherichia coli tryptophan synthetase suitable for investigating protein folding.Proceedings of the National Academy of Sciences, 1977
- Immunological measurements of conformational motility in regions of the myoglobin moleculeBiochemistry, 1977
- Comparison of Experimental Binding Data and Theoretical Models in Proteins Containing Subunits*Biochemistry, 1966
- Purification and Properties of the B Component of Escherichia coli Tryptophan SynthetaseJournal of Biological Chemistry, 1965
- A study of the catalytic properties of Escherichia coli tryptophan synthetase, a two-component enzymeArchives of Biochemistry and Biophysics, 1962
- The genetic control and cytoplasmic expression of “Inducibility” in the synthesis of β-galactosidase by E. coliJournal of Molecular Biology, 1959
- PROTEIN MEASUREMENT WITH THE FOLIN PHENOL REAGENTJournal of Biological Chemistry, 1951