Entero-cytolysin (EC) from Vibrio cholerae non-O1 (some properties and pore-forming activity).

A thermolabile extracellular entero-cytolysin (EC) from Vibrio cholerae non-O1 was purified by ammonium sulphate fractionation, DE-52 cellulose ion exchange chromatography, gel-filtration on Ultrogel AcA-44 and high performance liquid chromatography on a Mono Q. The purified EC had a molecular weight of 63 kD and an isoelectric point of 6.2.

NH2-terminal localization of that part of the staphylococcal enterotoxins polypeptide chain responsible for binding with membrane receptor and mitogenic effect.

It is established that the part of the SEA and SEC2 polypeptide chain responsible for the binding of these toxin proteins with the membrane receptor on the surface of rabbit thymocytes and mitogenic effect is localised in the NH2-terminal region of the molecule. The SEC2 splits in two fragments T1 (17 kdalton) and T2 (12.5 kdalton) under limited proteolysis by trypsin in the presence of 2-ME.

Membrane protein from rabbit T-lymphocytes, specifically binding staphylococcal enterotoxin A (SEA).

The presence of specific binding of SEA with membranes of lymphocytes from rabbit thymus is established. Components of a glycolipid nature are absent in the composition of the receptor complex for SEA on T-lymphocytes. Suitable conditions for the solubilization of the receptor membrane fraction by Triton X-100 are described.

Topology of the functions in molecule of staphylococcal enterotoxin Type A.

Four fragments (F1-F4) of SEA, obtained via papain proteolysis were separated and isolated as individual components by means of the SDS-electrophoresis in polyacrilamide gel. Molecular masses of the pairs F1 + F4 and F2 + F3 are equal to the mass of the intact toxin--a fact that supposes a cleavage of polypeptide chain in two regions of "disulphide loop" in a SEA molecule. Neither fragment possesses any enterpathogenic properties.

Properties of staphylococcal enterotoxin A under limited proteolysis.

1. Staphylococcal enterotoxin A (SEA) was exposed in a state of limited proteolysis to five kinds of proteolytic enzymes: papain, pepsin, pronase, trypsin and alpha-chymotrypsin. SEA was found to be sensitive to the action of three of them: papain, pepsin and pronase.

Purification and some properties of exotoxin from Corynebacterium ulcerans strain ATCC 9015.

Corynebacterium ulcerans strain ATCC 9015 develops during growth in environmental media an exotoxin which is lethal for guinea-pigs. The exotoxin has been purified by ion-exchange chromatography on DEAE-Sephadex A-50, affinity chromatography using immunosorbent techniques, and gel-filtration through Sephadex G-75. The exotoxin is of a protein nature and consists perhaps of two subunits.

Proof for the lack of diphtheria toxin in culture filtrates of Corynebacterium ulcerans strain ATCC 9015.

Extensive efforts to identify the diphtheria toxin in culture filtrates of C. ulcerans strain ATCC 9015 was unsuccessful. The culture filtrates did contain a component (called D-antigen) which formed a precipitin line with commercial diphtheria antitoxin.