Profile: The Native Antigen Company Ltd. specializes in the development and manufacture of native viral & bacterial antigens. Our antigens are used by pharmaceutical and IVD manufacturers in vaccine research and serology where high specificity and sensitivity are vital, and in academic microbiological research where reliable reagents are required for in vitro and in vivo work. Diptheria toxin is an endotoxin produced by corynebacterium diphtheria. It is a polypeptide chain consisting of two sub-units linked by disulphide bridges ? in vivo the B subunit binds to the cell surface which facilitates penetration of the cell by the A sub-unit. The toxin then catalyses ADP-ribosylation of eukaryotic aminoacyltransferase II using NAD as the substrate and thereby inhibiting protein synthesis.