Open AccessBinding of triton X-100 to diphtheria toxin, crossreacting material 45, and their fragments.
Author(s) -
Patrice Boquet,
Mitchell S. Silverman,
Alwin M. Pappenheimer,
Walter B. Ver
Publication year - 1976
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.73.12.4449
Subject(s) - diphtheria toxin , chemistry , sodium dodecyl sulfate , toxin , micelle , chromatography , cytoplasm , sodium , triton x 100 , biochemistry , pulmonary surfactant , organic chemistry , aqueous solution
Binding of the nonionic detergent [3H]Triton X-100 by diphtheria toxin, by the nontoxic serologically related protein crossreacting material (CRM) 45, and by their respective A and B fragments has been studied. If first denatured in 0.1% sodium dodecyl sulfate, all of the proteins with the exception of fragment A bind increasing amounts of Triton X-100, reaching a maximum of more than 40 mol bound per mol of protein when the detergent concentration exceeds its critical micelle concentration. No measurable amount of Triton X-100 is bound by native toxin or its A fragment of any concentration of the detergent. Undenatured CRM45 or its B45 fragment, on the other hand, readily became inserted into Triton X-100 micelles when the detergent reaches its critical micelle concentration. The results show that the toxin molecule contains a hydrophobic domain located on the portion of the B fragment that is linked to A. This region is masked in native toxin. Based on these findings, a model is proposed to describe how fragment B facilitates the transport of the enzymically active hydrophilic fragment A across the plasma membrane to reach the cytoplasm.