Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8394011 | Toxicon | 2018 | 45 Pages |
Abstract
A homodimeric l-amino acid oxidase enzyme (Cv-LAAOI) was isolated from the venom of Cerastes vipera (Egyptian Sand viper) using gel filtration followed by anion exchange chromatography. The molecular mass of Cv-LAAO is 120â¯kDa in its native form and 60â¯kDa in its monomeric form. The optimum enzyme activity was achieved on l-Leucine as a substrate in 50â¯mM buffer pH 7.5â¯at 50â¯Â°C. The Cv-LAAOI activity was significantly reduced by increasing the temperature over 40â¯Â°C, lost 75% of its activity at 60â¯Â°C and inhibited completely at 80â¯Â°C. The Cv-LAAOI attains the highest substrate specificity towards L-Met. The results have also indicated that Mn2+ enhances the enzyme activity by 10%, while Cu2+, Hg2+, Ni2+, Co2+ have suppressive effects on the Cv-LAAOI activity. On the other hand, EDTA has no significant effect on the enzyme activity. The kinetic parameters of Cv-LAAOI activity (Km, Kcat and Vmax) estimated on l-Leucine at pH 8 and 37â¯Â°C were found to be 2â¯mM, 12â¯Sâ1 and 16.7â¯Î¼mol/min/ml, respectively. In addition, the results have shown that Cv-LAAOI exhibits a significant bactericidal activity against gram-positive and gram-negative bacteria, particularly Staphylococcus aureus and Escherichia coli with MIC values of 20â¯Î¼g/ml. Moreover, Cv-LAAOI has exhibited a considerable cytotoxic activity against breast cancer cell line (MCF-7) with IC50 value 2.75â¯Â±â¯0.38â¯Î¼g/ml compared with different tumor cell lines (liver HepG2, lung A549, colon HCT116 and prostate PC3). Furthermore, Cv-LAAOI has triggered antiproliferative activity via extensive H2O2 generation as indicated by the increase in H2O2 and TBARS levels accompanied by the depletion in the catalase activity (CAT) in MCF-7 treated cells compared to the untreated ones. Thus, these findings clearly indicate that Cv-LAAOI has a selective cytotoxic effect on breast cancer cell line, demonstrating a great prospective for future use in cancer therapy.
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Authors
Walaa H. Salama, Nihal M. Ibrahim, Amr E. El Hakim, Roqaya I. Bassuiny, Manal M. Mohamed, Fatma M. Mousa, Mamdouh M. Ali,