Abstract
α-N-acetylgalactosaminidase (EC 3.2.1.49) (alpha-NaGalase) catalyzes the hydrolysis of N-acetamido-2-deoxy-α-d-galactoside residues from non-reducing ends of various complex carbohydrates and glycoconjugates. It is known that human cancer cells express an alpha-NaGalase, which accumulates in the blood plasma of patients. The enzyme deglycosylates the Gc protein-derived macrophage activating factor (GcMAF) and inhibits macrophage activity acting as an immunosuppressor. The high specific activity 0.033 ± 0.002 μmol mg−1 min−1 of the enzyme was found in human colon carcinoma cells DLD-1. The alpha-NaGalase of DLD-1 cells was isolated and biochemical characterized. The enzyme exhibits maximum activity at pH 5.2 and temperature 55 °C. The Km is 2.15 mM, Vmax–0.021 μmol min−1 mL−1, kcat–1.55 min−1 and kcat/Km–0.72 min−1 mM−1 at 37 °C, pH 5.2. The effects of fucoidan from the brown alga Fucus evanescence on the activity of alpha-NaGalase in human colon carcinoma DLD-1 cells and on the biosynthesis of this enzyme were investigated. It was shown that fucoidan did not inhibit free alpha-NaGalase, however, it reduced the expression of the enzyme in the DLD-1 cells at IC50 73 ± 4 μg mL−1.
Highlights
According to the statistics of the World Health Organization, the colon is the second organ after lung in the human body, which is most often affected by cancer
In the present study several human cancer cell lines such as human melanoma SK-MEL-28 and RPMI-7951, breast cancer T-47D and MDA-MB-231, and colon cancer DLD-1 and HT-29 were screened for the activity of alpha-NaGalase
We studied the biochemical characteristic of alpha-NaGalase, isolated from human colon carcinoma cellEnzyme lines DLD-1
Summary
According to the statistics of the World Health Organization, the colon is the second organ after lung in the human body, which is most often affected by cancer. 600 thousand cases of colon cancer are fixed. That’s why the improvement of colon cancer therapy is crucial task of oncology. They catalyze the hydrolysis of the terminal α-linked N-acetylgalactosamine residues from the non-reducing ends of various complex carbohydrates and glycoconjugates. Glycolipids, glycopeptides, and glycoproteins, blood group A erythrocyte antigens [2,3,4], lipopolysaccharides of the cell walls and capsules of bacteria [5,6,7] are physiological substrates for alpha-NaGalase
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