Identification of functionally active fragments of staphylococcal enterotoxin B.

It has been found that staphylococcal enterotoxin B contains a proteolysis-sensitive sequence in the cysteine loop formed by two half-cystines located in the middle of the toxin polypeptide chain. Fragments of the enterotoxin formed as a result of its digestion in this region have been isolated, their N-terminal sequences have been determined and sites of proteolysis have been identified. It has been demonstrated that the N-terminal fragment of staphylococcal enterotoxin B is capable of activating T cell proliferation in the culture of human mononuclear cells practically to the same degree as the intact enterotoxin. The toxin's C-terminal fragment possesses an ability to activate calmodulin-dependent enzymes and is probably the toxicogenic part of the enterotoxin.

Preparative in vitro synthesis of bioactive human interleukin-2 in a continuous flow translation system.

Recombinant human interleukin-2 has been synthesized in vitro in a continuous flow translation system based on the wheat germ extract. In the course of translation of mRNA the interleukin-2 becomes aggregated due to the adsorption of this protein onto the ribonucleoprotein complex. This process correlates with the cessation of translation that is usually observed in 25-30 min. This can be prevented by the use of a flow system that allows continuous removal of the synthesized protein and maintains a steady concentration of all the necessary components. This approach permitted a yield of 1,500 protein molecules per mRNA molecule. The interleukin obtained promotes the proliferation of the interleukin-2-dependent CTLL-2 cell line. The biological activity of interleukin-2 not subjected to oxidative refolding was 10(5) units per milligram of protein.

Cell-free translation in reversed micelles.

Cell-free translation in reversed micelles (RM) of surfactants in organic solvents is demonstrated using as an example the synthesis of human interleukin-2 by the wheat germ translation system solubilized in Brij 96 (oleyl-poly(10)oxyethylene ether) RM in cyclohexane. The translation system components and the product were recovered from the RM system by acetone precipitation. The recovery and translation reaction yields depended on the degree of surfactant hydration. The translation yields in Brij 96 RM were close to that observed in regular aqueous solution. The Brij 96 RM system is regarded as a promising media for the cell-free synthesis of hydrophobic proteins. Meanwhile, no translation reaction was observed in Aerosol OT (sodium bis(2-ethylhexyl) sulfosuccinate) RM in octane, which presumably is due to the ability of Aerosol OT to bind Mg2+ ions necessary for the functioning of the translation apparatus.

[Preparation and characteristics of monoclonal antibodies against GTP-binding protein from the bovine retina]. / Poluchenie i kharakteristika monoklonal'nykh antitel k GTP-sviazyvaiushchemu belku iz setchatki glaz byka.

Five monoclonal antibodies against the native GTP-binding protein (transducin) from bovine retina have been prepared. By immunoblotting and immunoenzymatic analysis of the isolated alpha- and gamma-subunits of transducin and the beta gamma-subunit complex it was determined that two monoclonal antibodies A3G7 and A3C10 recognize linear antigenic determinants on the alpha-subunit, two other, A3E4 and 3B3, bound specifically to the gamma-subunit, and monoclonal antibodies 1C3 interact only with native transducin. Both antibodies against the alpha-subunit inhibited transducin GTPase activity, whereas antibodies A3E4, 3B3 and 1C3 did not affect it.