Chemical and physical properties of cholera exo-enterotoxin (choleragen) and its spontaneously formed toxoid (choleragenoid)

LoSpalluto, Joseph; Finkelstein, Richard A.

doi:10.1016/0005-2795(72)90265-6

Cited by 134 publications

(58 citation statements)

References 21 publications

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“…This agrees well with other observations on strain variability (Truszcynski and Ciosek, 1972). One of the toxins with a MW in the medium range apparently fragmented during ultrafiltration whilst the other remained stable, indicating that their molecular structures may have been quite different and that the interrelationship of enterotoxins may not be quite as simple as suggested by Smith and Gyles (1970a); moreover, it would seem that, in molecular terms, E. coli enterotoxin may not be directly comparable with Vibrio cholerae toxin (Finkelstein, Peterson and Lospalluto, 1971 ;Lospalluto and Finkelstein, 1972). The MW of the low-MW toxin is very close to that of cyclic 3',5'-adenosine monophosphate (c-AMP; MW 347) which has been implicated in E. coli enteritis (Al-Awqati et al, 1972).…”

Section: Discussionmentioning

confidence: 99%

Separation and Purification of Enterotoxins From a Strain Escherichia Coli Pathogenic for Pigs

Mitchell¹,

Tame

Kenworthy

1974

Journal of Medical Microbiology

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) was used as by Mitchell et al. (1974).Enterotoxic supernates were prepared from defined-medium cultures of E. coli by centrifugation for 20 min. at 75,000 g. These prepations were then either (a) freeze-dried and redissolved in distilled water to give 10-to 25-fold concentration, or (b) reverse-dialysed against 30% w/v polyethylene glycol for 24 hours to give between 7-and 15-fold concentration ; the cellulose membrane used had a molecular-weight exclusion of between 104 and 2 x 104 daltons. Concentration methods.

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Section: Discussionmentioning

confidence: 99%

Separation and Purification of Enterotoxins From a Strain Escherichia Coli Pathogenic for Pigs

Mitchell¹,

Tame

Kenworthy

1974

Journal of Medical Microbiology

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“…Seven L chains associated with one H component would possibly give a molecule with the 84000 mol. wt reported for the toxin from ultracentrifuge analyses (LoSpalluto & Finkelstein, 1972) and this model would fit with the observed ratio 2: I of the L and H subunits in the toxin. Probably the L chains and the H component, the latter possibly a disulphide-bridged dimer, are held together with non-covalent bonds.…”

Section: Discussionmentioning

confidence: 99%

“…However, the recent demonstration of amino acid differences between the two proteins (LoSpalluto & Finkelstein, 1972) indicated peptide differences between them. By use of SDS polyacrylamide electrophoresis, which permits dissociation and separation of non-covalently bound components, we were able to demonstrate two types of subunit in the toxin, only one of which was demonstrable in the toxoid.…”

Section: Discussionmentioning

confidence: 99%

“…This permitted the separation and isolation of the faster filtering H component from the slower filtering L component. However, the recovery of the H component was comparatively poor, which might explain that only one size of subunit was demonstrated in ultracentrifuge analyses of cholera toxin in dissociating milieu (LoSpalluto & Finkelstein, 1972). The purity of the cholera toxin and toxoid preparations has been assessed by various methods (Finkelstein & LoSpalluto, 1970).…”

Section: Discussionmentioning

confidence: 99%

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Subunit Structure of Cholera Toxin

Lönnroth

Holmgren

1973

Journal of General Microbiology

136

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S U M M A R YTwo types of subunit, with molecular weights estimated to be 28000 and 8000, were demonstrated in the cholera exo-enterotoxin by sodium dodecylsulphate polyacrylamide electrophoresis. The light (L) component but not the heavy (H) was demonstrable in the antigenically identical natural toxoid. A split of the H component by reduction and alkylation suggested it to be a disulphide-bridged dimer.Gel filtration at acid pH permitted separation of the H and L subunits in isolated form. Fractions with isolated subunits were non-toxic (skin test), in contrast to fractions with intermediate filtration rate containing both subunits.Fractions with a L: H ratio of about 3.5 were even more toxic than the intact toxin (L: H ratio about 2). Addition of the isolated subunits to toxic fractions generally caused inhibition and only exceptionally potentiation of toxicity.The data suggest that the cholera toxin might consist of an aggregate of seven L and one H subunits while the natural toxoid seems composed of only the aggregated L chains.

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“…The ability of the toxin to enhance adenylate cyclase activity has been directly or indirectly demonstrated in a variety of tissues. Significant progress has been made in elucidating the structure of cholera toxin (2)(3)(4)(5)(6) and identifying a cell membrane receptor (7)(8)(9)(10), but the mechanism by which the toxin, once bound to receptor, stimulates adenylate cyclase is not understood (11).…”

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confidence: 99%

Mode of Action of Cholera Toxin: Stabilization of Catecholamine-Sensitive Adenylate Cyclase in Turkey Erythrocytes

Field

1974

Proc. Natl. Acad. Sci. U.S.A.

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Preincubating turkey erythrocytes with cholera toxin alters their adenylate cyclase (EC 4.6.1.1) system: basal activity, maximal epinephrine-stimulatable activity, and affinity of the enzyme reaction for epinephrine are all increased. Pretreatment of erythrocytes with choleragenoid prevents these changes. Cholera toxin does not alter [PHlepinephrine uptake by intact erythrocytes. The increase in epinephrine-stimulatable cyclase activity appears to occur at the expense of fluoridestimulatable activity, which is decreased by the toxin. In lysates from both toxin-treated and control cells, maximally stimulating amounts of epinephrine and fluoride, when added in combination, have a nearly additive effect on cyclase activity. These observations suggest that the adenylate cyclase system of the turkey erythrocyte may exist in two interconvertible forms, one that is catecholamine-responsive but fluoride-insensitive, and another that is fluoride-sensitive but not coupled to catecholamine receptors. Cholera toxin appears to stabilize the enzyme in its hormone receptor-coupled form.

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Chemical and physical properties of cholera exo-enterotoxin (choleragen) and its spontaneously formed toxoid (choleragenoid)

Cited by 134 publications

References 21 publications

Separation and Purification of Enterotoxins From a Strain Escherichia Coli Pathogenic for Pigs

Separation and Purification of Enterotoxins From a Strain Escherichia Coli Pathogenic for Pigs

Subunit Structure of Cholera Toxin

Mode of Action of Cholera Toxin: Stabilization of Catecholamine-Sensitive Adenylate Cyclase in Turkey Erythrocytes

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