Diphtheria toxin
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Diphtheria toxin is an exotoxin secreted by Corynebacterium diphtheriae, the pathogen bacterium that causes diphtheria.
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Structure
Diphtheria toxin is a single polypeptide chain of 535 amino acids consisting of two subunits linked by disulfide bridges. Binding to the cell surface of the less stable of these two subunits allows the more stable part of the protein to penetrate the host cell.[1]
Mechanism
It catalyzes the ADP-ribosylation eucaryotic elongation factor-2 (eEF2), inactivating this protein. It does so by ADP-ribosylating the unusual aminoacid diphthamide. In this way, it acts as a RNA translational inhibitor. The exotoxin A of Pseudomonas aeruginosa uses a similar mechanism of action.
Lethal dose
Diphtheria toxin is extraordinarily potent.[1] The lethal dose for humans is about 0.1 μg/kg of pure protein. A massive release of toxin into the body will likely cause lethal necrosis of the heart and liver.[2]
History
Diphtheria toxin was discovered in 1890 by Emil Adolf von Bering.
Clinical use
The drug denileukin diftitox uses diphtheria toxin as an antineoplastic agent.
References
- ↑ 1.0 1.1 Murphy JR (1996). Corynebacterium Diphtheriae: Diphtheria Toxin Production In: Baron's Medical Microbiology (Baron S et al, eds.), 4th ed., Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.
- ↑ Pappenheimer A (1977). "Diphtheria toxin.". Annu Rev Biochem 46: 69-94. PMID 20040.
External links
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
