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According to the results of quantum chemistry calculation and the present research status in the relationship between the structures and the functions of DT, the E154 in DT catalyzing domain was mutated to aspartic acid and arginine in order to study the effects of the alteration on the biological activities. By means of gene site-direct mutation, two mutated genes were prepared and the high performance expression was obtained in E.coli system. The results of toxcity studies indicated that the acute toxicity in guinea pig and cytotoxicities of mutant E154D increased slightly in compared with those of recombination wild toxin, and contrarily, those of E154R decreased obviously.
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Objective To assess the toxicity risks of diphenylchlorarsine (DA) to environments, human beings and livestock. Methods Totally 120 mice were randomly divided into 6 groups and given DA by gastric gavage at the doses of 32, 30, 28, 26, 24, 22 mg/kg respectively for LD_(50) of DA in mice. The toxicity of DA in rat skin were evaluated by smearing 50 ?l DA at the concentrations of 140, 70, 35, 17.5, and 8.8 mg/ml to an area of 4 cm2, and that of eyes exposure was carried out by dropping 10 ?l DA of 140.7, 70, 7, 0.7 mg/ml in rat eyes. The counterpart skin area and eyes served as control. Results LD_(50) of DA in mice was 28.07 mg/kg, the estimated doses for no-observed-adverse-effect levels (NOELs) were 8.8 mg/ml (0.44 mg) to the skin and 0.7 mg/ml (0.014 mg) to the eyes respectively. Conclusion DA can induce the injuries on the liver, kidneys, esophagus and stomach. High concentration of DA can cause inflammation of the skin and lens opacification, even blind.
RESUMEN
Objective:To prepare highly purified Staphylococcal enterotoxin B(SEB) by affinity chromatography and test its activities.Methods:Anti-SEB McAb(1D2) purified by precipitation method with caprylic acid was coupled to Sepharose 4B. And then the SEB was isolated using an affinity chromatography column. In addition, we analyzed the superantigen activity and antigen activity of SEB.Results:The purification efficiency of SEB was 60.71% by affinity chromatography. Its purity was higher than those of standard preparation and the SEB purified by ion change chromatography. At the same time, the purified SEB by affinity chromatography possesses favourable activities of superantigen and antigen.Conclusion:McAb affinity chromatography could be used for purification of SEB with high efficiency.