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S van Heyningen

Publications and source records attributed to S van Heyningen.

34 records · Page 2Linked to original sources
PubMed1982

Cholera toxin.

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Adenosine Diphosphate Ribose↗
PubMed1981

The hydrophobicities of cholera toxin, tetanus toxin and their components.

1. Charge-shift electrophoresis showed that cholera toxin and its subunits have no hydrophobic surfaces. 2. Amino-acid composition and sequence data suggested that the proteins have no masked hydrophobic regions. 3. The A subunit of cholera toxin may interact with polar molecules in the membrane to exert its effect inside the cell. 4. The only hydrophobic part of tetanus toxin was the H-chain.

Amino Acids↗
PubMed1980

Tetanus toxin.

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Animals↗
PubMed1978

The adenylate cyclase-activating activity of cholera toxin is not associated with a nicotinamide--adenine dinucleotide glycohydrolase activity.

The NAD+ glycohydrolase activity of cholera-toxin samples can be separated from their adenylate cyclase-activating activity by polyacrylamide-gel electrophoresis and is inhibited by sodium dodecyl sulphate (which does not inhibit the action of toxin on cells), but not by antibodies to pure toxin. It is therefore probably not a true property of the toxin.

Adenylyl Cyclases↗
PubMed1977

Activity of covalently cross-linked cholera toxin with the adenylate cyclase of intact and lysed pigeon erythrocytes.

Reaction of cholera toxin with NN'-bis(carboximidomethyl)tartaramide dimethyl ester produced several cross-linked species that had subunit B (which binds to the cell surface) and peptides A1 (which activates adenylate cyclase) and A2 all covalently joined together. This cross-linded material had activity with pigeon erythrocytes that was comparable in all respects with that of native toxin. It activated the adenylate cyclase of whole cells, showing a characteristic lag phase, and this activation was increased if the cells had been preincubated with ganglioside GM1, but abolished if the protein had been preincubated with the ganglioside. It activated the enzyme in lysed cells more strongly and without the lag phase. These results show that the toxin is active even when peptide A1 cannot be released from the rest of the molecule.

Adenylyl Cyclases↗
PubMed1977

Cholera toxin.

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Adenylyl Cyclases↗
PubMed1976

The subunits of cholera toxin: structure, stoichiometry, and function.

The toxin of Vibrio cholerae dissociates into subunit A and an aggregate of subunit B (choleragenoid); the dissociation is rapid under denaturing conditions and slow at neutral pH. Subunit A has a molecular weight of 27,000 daltons (measured by sedimentation equilibrium or gel chromatography) and has two polypeptide chains (mol wt, approximately 22,000 and 5,000 daltons) joined by disulfide bonds. The molecular weight of subunit B in 6 M guanidine hydrochloride is 14,000 daltons when determined by sedimentation equilibrium or gel chromatography, although dodecylsulfate gel electrophoresis suggests a lower value. These results suggest a structure of AB4 for the toxin; studies of cross-linking with methyl-4-mercaptobutyrimidate confirm this structure. The properties of antibodies both to cholera toxin and to choleragenoid are compatible with this structure, but subunit A has very low immunogenicity. Subunit A by itself is active, and this activity is abolished by a large excess of antitoxin but not by choleragenoid, anticholeragenoid, or ganglioside GM1 (galactosyl-N-acetylgalactosaminyl [sialosyl] lactosyl ceramide; GGnSLC). It is suggested that the function of subunit B is not to interact directly with the adenylate cyclase system, but to bind to the cell membrane and facilitate the interaction of subunit A.

Antibodies, Bacterial↗