Purification, characterization and in vitro anti-tumor activity of proteins from Arca subcrenata Lischke

Two purified proteins G-6 and G-4-2 were obtained from Arca subcrenata Lischke using the homogenization, salting-out with ammonium sulfate, ion-exchange chromatography and gel filtration chromatography techniques. The purity of G-6 and G-4-2 was over 96%, as measured by RP-HPLC. G-6 and G-4-2 were measured by SDS-PAGE and IEF-PAGE to have molecular weights of 8.2 kDa and 16.0 kDa, and isoelectric points of 6.6 and 6.1, respectively. The amino acid constituents of G-6 and G-4-2 were also determined. The existence of saccharides in G-6 was demonstrated by the phenol-sulfuric acid method. G-6 and G-4-2 inhibited the proliferation of human tumor cells in vitro. By MTT assay, the IC(50) values of G-4-2 were 22.9 microg/mL, 46.1 microg/mL and 57.7 microg/mL against Hela, HL-60 and KB cell lines, respectively, and the IC(50) value of G-6 against HL-60 cell line was measured to be 123.2 microg/mL.