Identification of a molten globule like state in HC-N fragment of botulinum neurotoxin A: shedding light on the poorly-known features of a conserved sub-domain.

C-terminal fragment of the Botulinum neurotoxin A comprises two sub-domains including H(C)-N and H(C)-C. Here, the conformational change of H(C)-N was studied by spectroscopic techniques. The results indicated that the partially unfolded state forms during unfolding of H(C)-N. This finding may shed light on poorly--known features of the protein.