Differential conformational environment of tryptophan in epsilon native prototoxin and active toxin from Clostridium perfringens type D

Abstract

The tryptophan content of Clostridium perfringens type D epsilon protoxin and toxin was found to be one residue per molecule of protein. N-bromosuccinimide in the presence of urea cleaves the tryptophan with total loss of lethality in both toxin and prototoxin. Fluorescence spectroscopy, circular dichroism (CD) and 10% ethylene glycol solvent perturbation studies showed that the tryptophan in epsilon toxin and that in prototoxin have different conformational environments. The tryptophan is more on the surface in the prototoxin than in the toxin molecule. NBS causes total loss of lethality of the toxin with its ellipticity coming to almost zero in the near UV region of the CD.