Class II major histocompatibility complex (MHC) molecules present peptides derived from processed antigen to antigen-specific CD4-positive T cells. In addition, class II molecules bind with high affinity another class of antigens, termed superantigens. T cell stimulation by superantigens depends almost exclusively on the V beta segment expressed by the T cell receptor (TCR). Mapping of the supe...

Ricin is a highly toxic plant toxin of Ricinus comtnunis seeds, commonly known as castor seeds. The toxin was extracted and purified using affinity and size exclusion chromatography. The purity of ricin was evaluated by the sodium dodecylsulphate-polyacrylamide gel electrophoresis. Purified ricin gives a single band under non-reduced condition and two bands under reduced condition. The molecula...

nigella sativa (n. sativa), which belongs to the botanical family of ranunculaceae, is a widely used medicinal plant all over the world. n. sativa seeds and oil have been used in the treatment of different diseases. various studies on n. sativa have been carried out and a broad spectrum of its pharmacological actions have been established which include antioxidant, antidiabetic, anticancer, ant...

A 10-aa motif in transmembrane helix 1 of diphtheria toxin that is conserved in anthrax edema factor, anthrax lethal factor, and botulinum neurotoxin serotypes A, C, and D was identified by blast, clustal w, and meme computational analysis. Using the diphtheria toxin-related fusion protein toxin DAB(389)IL-2, we demonstrate that introduction of the L221E mutation into a highly conserved residue...

Toxin-antitoxin (TA) systems are essential for bacterial persistence under stressful conditions. In particular, Mycobacterium tuberculosis express VapBC TA genes that encode the stable VapC toxin and the labile VapB antitoxin. Under normal conditions, these proteins interact to form a non-toxic TA complex, but the toxin is activated by release from the antitoxin in response to unfavorable condi...

Most reports dealing with vaccines against botulinum toxin have focused on the injection route of administration. This is unfortunate, because a mucosal vaccine is likely to be more efficacious for patients and pose fewer risks to health care workers and to the environment. Therefore, efforts were made to generate a mucosal vaccine that provides protection against the botulinum serotypes that t...

In a preceding paper it was shown that low concentrations of diphtheria toxin, in the presence of NAD 1 as an essential cofactor, inhibit the incorporation of amino acids into TCA-precipitable peptides in mammalian cell extracts (1). Collier (2) has demonstrated that this inhibitory action of the toxin is due to the specific inactivation of transferase II , one of the highly labile soluble enzy...