Cholera toxin is an oligomeric protein of MW 84kD and consists of a single A subunit surrounded by five B subunits. It is a potent activator of adenylate cyclase and is the pathogenic agent responsible for the symptoms of cholera. The B subunit (choleragenoid) is responsible for the binding of the holotoxin to G M1 ganglioside receptors on mammalian cell surfaces and facilitates entrance of the A subunit into the cell. The A subunit bears the ADP-ribosyl-transferase activity, which deregulates the G sprotein causing activation of adenylate cyclase. Due to the ubiquitous occurrence of the GM1 ganglioside receptor on eukaryotic cell membranes, cholera toxin activates adenylate cyclase in a wide variety of systems.
Cholera toxin has become a powerful research tool not only in microbiology, but in the fields of physiology, cell biology and biochemistry, as well. Because of the effect on adenylate cyclase, cholera toxin and its purified A subunit are frequently used for the study of signal transduction mechanisms. In addition, cholera toxin acts as an adjuvant through the stimulation of B-lymphocytes. The cholera toxin B subunit alone is used for track tracing in neurological research, taking advantage of GM1 ganglioside binding and retrograde transport.
Cholera toxin is isolated from Vibrio cholerae type Inaba 569B by modification of the methods of Rappaport et al. and Mekalanos et al. When equal weights are compared, the A subunit exhibits 3 to 5 times the transferase activity of the holotoxin. The B subunit exhibits little to no transferase activity.
Cholera toxin and native subunits all undergo treatment for the removal of contaminating endotoxin and are sterile as packaged.
Activity:When compared to a standard solution of B subunit at the same protein concentration, exhibits comparable ganglioside binding activity in a hemagglutination assay. In immunodiffusion studies, shows comparable immunoprecipitation to unconjugated standard when reacted against a specific antiserum to B subunit. Each lot is accompanied by a certificate of analysis indicating the ug quantity of FITC bound per mg of cholera toxin B subunit (choleragenoid), assuming an extinction coefficient at 493nm of 85,200M-1cm2 for FITC.
Storage:Lyophilized powder stoppered under vacuum. It is recommended that this material be stored at 4°C prior to and following reconstitution. DO NOT FREEZE. This product is light sensitive.
Handling:Good laboratory technique should be employed in the safe handling of this product. This requires observing the following practices:1. Wear appropriate laboratory attire including a lab coat, gloves and safety glasses. 2. Do not mouth pipette, inhale, ingest or allow to come into contact with open wounds. Wash thoroughly any area of the body which comes into contact with the product. 3. Avoid accidental autoinoculation by exercising extreme care when handling in conjunction with any injection device.
仕様
Size：200ug
Purity：The transferase activity of this lot was nearly zero when compared to a comparable amount of cholera toxin standard in an ADP-ribosylation assay. This preparation migrates as a single major band in disc gel electrophoresis under nondenaturing conditions. The R280/260 of each preparation is reported.
Form：Supplied as a lyophilized powder in 0.01 M sodium phosphate, pH 7.5. No preservative added. Labeled with fluorescein isothiocyanate, isomer I (FITC) by a modification of the method of Wood et al.
