Physical-Chemical and Cytotoxic Properties of Bacillus subtilis IMV B-7724 Extracellular Lectin

Aim. To study the chemical composition, sugar specificity and physicochemical properties of the extracellular lectin isolated from Bacillus subtilis ІМV В-7724. Methods. Biochemical, spectrophotometric, immunological and cultural methods were used to assess the physicochemical and a number of biological properties of lectin isolated from the culture fluid of bacteria B. subtilis ІМV В-7724. Molecular weight of the lectin was estimated in polyacrylamide gel electrophoresis. Analysis of the elemental composition was done using Perkin-Elmer 2400 CHNS analyzer. Temperature and pH stability of lectin were examined based on residual hemagglutination activity of the lectin. Cytotoxic activity was determined by the MTT-assay. The statistical analysis was made using Student’s t-test. Results. B. subtilis IMV B-7724 lectin is a glycoprotein (protein – 86.0%, carbohydrates – 7.0%) with molecular weight of 18–20 kDa (major). Analysis of the elemental composition revealed that it contains 34.00% of carbon, 7.04% of hydrogen, 16.61% of nitrogen, 42.35% of oxygen. Amino acid composition analysis determined that it is rich in leucine, tyrosine and phenylalanine. The lectin exhibited high sugar-binding specificity toward N-acetylneuraminic and N-glycolylneuraminic acids (minimal inhibitory concentration – 0.3 mM for both sugars). The lectin is heat and acid stable, has long shelf life. Conclusions. These results provide the rationale to pursue further investigation for possible ways and modes of B. subtilis IMB B-7724 lectin application in clinical settings.