| Summary: | 碩士 === 中華大學 === 資訊工程學系 === 95 === Proteins are important for their catalytic function in physiology and biology. Proteins are especially crucial in regulating signal transduction pathways via protein-protein interaction. Post-translational modification controls these protein interactions through adding phosphate groups by kinases or removing phosphate groups by phosphatases. While kinases are better understood, studies of phasphatases are still rudimentary. The present study is mainly focused on understanding the de-phosphorylation function of phosphatases. Among protein tyrosine phosphatase (PTP) family, the dual-specific protein phosphatases (DSPs) are major members. DSPs was named based on their ability of simultaneously de-phosphorylation Tyrosine(Y)-phosphate and Serine(S)/Threonine(T)- phosphate on the substrates to regulate the substrate activity. We first searched conserved motif of DSP active sites with sequences of -CXXXXXR- (X could be any amino acid), then we collect the four spatial coordinates from the substrate-interacting Cysteine (C) and Arginine (R), the catalytic Aspartate (D), and the substrate phosphate (P). The distances measured from C, R, and D to P were calculated as interaction parameters, and distances between C, R, and D were taken as active site parameters. These parameters were used to predict whether unknown might have possible active site cavity of DSPs. The α-ball protein surface modeling was applied to screen unknown proteins for the possible presence of active site topology before entering DSP-parameter comparison. The radius of the root group of the phosphate uses 2.15Å to 5.06Å between to make the test, the most accurate with the position of 2.15Å houses of activation position that can be predicted. We were able to predict the active sites of 16 structure-solved DSPs as well as 25 PTPs.
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