Study On The Structure And Reaction Mechanism Of Antitumor Drug Target Protein: DUSP26 And Tks4

Investigating the relationship between structure and function of anti-tumor target protein is the necessary step in the screening novel anti-tumor drugs process. In this study, structural and functional assay of two anti-tumor target proteins from human, dual-specificity phosphatase 26 (DUSP26) and Tks 4 had been carried out. In this paper, investigation of reaction mechanism uning the enzyme kinetic assay and inhibitors idenfication of DUSP26 using computer aided drug screening method were reported in part I. Results of priliminary crystallographical studies of the C-terminal of Src homology 3 (SH3) domain of human Tks4 were reported in part II.DUSP26 is a new anti-tumor target protein found in anaplastic thyroid cancer (ATC) et al. turmor tissues. The crystal structure of catalytic domain of DUSP26 had been determined successfully. The reaction mechanism of DUSP26 has not been determined. To identify the novel anti-turmor drugs, we investigated the reaction mechanism detail of DUSP26 using enzyme kinetics assay with the p-nitrobenzene phosphate (p-NPP) as the substrate. Based on results of the enzyme kinetics assay, a hypothetical reaction mechanism and a drug binding site in the DUSP26 molecule had been identified. Then the pharmacophore model had been designed and inhibitor candidates of DUSP26 identification from the microbial natural products database in institute of medicinal biotechnology, Chinese academy of medical science & Peking union medical college and the compounds database in J & K corporation had been carried out using virtual screening.232 compounds had been identified as the inhibtor candidates. The inhibitory activity of these inhibtor candidates was judged using enzyme kinetic assay with p-NPP as the substrate.8 compounds show inhibitory activity. The inhibitory activity of 2-hydroxy-4-{6-[(5Z)-5-[(4-methylphenyl)methylidene]-4-oxo-2-sulfanylidene-1,3-thiazolidin-3-yl]hexanamido} benzoic acid is stronger than the compound NSC-87877, which is only known inhibitor of DUSP26. These results suggest that the hypothetical reaction mechanism is real reaction mechanism of DUSP26. The compound may be as a anti-turmor drug candidite targeting DUSP26.The three-dimensional structure of human Tks4, which is a known anti-tumor drug target protein, has not been determined. To understand the relationship between the structure and function, crystallographical studies of C-terminal SH3 domain of human Tks4 had been carried out in this study. So far, the C-terminal SH3 domain of human Tks4 was expressed in Escherichia coli, purified, crystallized and X-ray diffraction data were collected. The crystal parameters had been determined. To solve the crystal structure, the isomorphous replacement method is being utilized.