Expanding our knowledge of protein tyrosine phosphatase-like phytases : mechanism, substrate specificity and pathways of myo-inositol hexakisphosphate dephosphorylation

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Puhl, Aaron A.
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2006
A novel bacterial protein tyrosine phosphatase (PTP)-like enzyme has recently been isolated that has a PTP-like active site and fold and the ability to dephosphorylate myo-inositol hexakisphosphate. In order to expand our knowledge of this novel class of enzyme, four new representative genes were cloned from 3 different anaerobic bacteria related to clostridia and the recombinant gene products were examined. A combination of site-directed mutagenesis, kinetic, and high-performance ion-pair chromatography studies were used to elucidate the mechanism of hydrolysis, substrate specificity, and pathways of Ins P6 dephosphorylation. The data indicate that these enzymes follow a classical PTP mechanism of hydrolysis and have a general specificity for polyphosphorylated myo-inositol substrates. These enzymes dephosphorylate Ins P6 in a distributive manner, and have the most highly ordered pathways of sequential dephosphorylation of InsP6 characterized to date. Bioinformatic analyses have indicated homologues that are involved in the regulation of cellular function.
x, 138 leaves ; 29 cm.
Dissertations, Academic , Phytases , Protein-tyrosine kinase , Phosphorylation