Tetanus neurotoxin heavy chain C-terminal fragment (TeNT Hc or TeNT HC fragment C)

The **tetanus neurotoxin heavy chain C-terminal fragment** (commonly called "fragment C" or "TeNT Hc") is a ~50 kDa protein domain derived from the C-terminal portion of the tetanus neurotoxin heavy chain, produced by *Clostridium tetani*. This fragment is responsible for the highly specific binding of the toxin to neuronal membranes, primarily through recognition of complex gangliosides (especially GT1b and GD1b) and a GPI-anchored protein receptor on neurons[1][3][7][9]. The fragment does not possess the catalytic (protease) or translocation functions of the full toxin, making it non-toxic and suitable for experimental and therapeutic applications. Fragment C is the principal immunogenic region of the tetanus toxin and is frequently used as a carrier protein in conjugate vaccines, as well as a tool for neuronal delivery and neuroprotection research. Its unique retrograde transport capabilities have made it an important probe for neuroanatomical mapping and a potential vehicle for targeted delivery of therapeutics in the nervous system[5][1].

Other names

Fragment C of tetanus toxinTetanus toxin heavy chain fragment CTT heavy chain fragment CTeNT HcTeNT HC fragment C

For vaccines and antibodies, neutralization occurs as antibodies bind to fragment C, blocking cell binding and uptake of the toxin. Experimental inhibitors, such as small molecules or peptides, prevent neuronal intoxication by blocking ganglioside or protein receptor binding sites on fragment C. Additionally, fragment C is utilized as a non-toxic carrier for vaccine or drug delivery to neurons due to its inherent neuronal targeting properties.