Diphtheria Toxin CRM197, Mutant is a natural genetically inactive diphtheria toxin (mutant) produced in the native host, Corynebacterium diphtheriae.
Corynebacterium diphtheriae is a Gram-positive, bacterium which infects epithelial cells of the upper respiratory tract and produces diphtheria toxin. Diphtheria toxin is proteolytically cleaved forming a two part toxin, held together by a disulfide bridge. The amino-terminal carries the toxin's enzymatic activity, capable of ADP-ribosylation and inactivation of translation elongation factor 2 (EF-2). The carboxy-terminal domain binds to specific host receptors, the heparin-binding EGF-like growth factor (HB-EGF) on human epithelial cells and translocates the catalytic domain into the cell. After binding to the cell receptor, the diphtheria toxin is taken up by endocytosis, the pH of the endocytic vesicle drops, and the translocation region of the toxin helps gulde the catalytic domain into the host cytoplasm where it is released. Within the cytoplasm, the diphtheria toxin catalytic domain ADP ribosylates EF-2, terminating protein synthesis and causing the death of the cell. Diphtheria toxin is highly potent, and as little as one catalytic domain is thought to cause cell death. In cell culture, diphtheria toxin inhibits protein synthesis and causes death in cells carrying the HB-EGF receptor. This toxin has been used to specifically eliminate receptor-expressing cells in transgenic mice.
When reconstituted with 500 ul of sterile purified water is in 0.01 M Sodium phosphate with 5% lactose, pH 7.4. Handle product gently, do not vortex.
The endotoxin content, determined using a kinetic chromagenic LAL assay, is 2 EU/mg.
This product is supplied as a lyophilized powder, sealed under vacuum. Store at 2-8 centigrade prior to reconstitution. Store at -20 centigrade after reconstitution.
Good laboratory technique should be employed in the safe handling of this product. Wear appropriate laboratory attire including a lab coat, gloves and safety glasses. Nitrile gloves are recommended when handling lyophilized material. This product is intended for research purposes by qualified personnel only. It is not intended for use in humans or as a diagnostic agent.