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Purification and characterization of two members of the protein tyrosine phosphatase family

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Date Issued:
2009
Summary:
Two protein tyrosine phosphatases, dual specificity phosphatase PVP and low molecular weight phosphatase WZB were purified and characterized. PVP was expressed as inclusion bodies and a suitable purification and refolding method was devised. Enzyme kinetics revealed that p-nitrophenylphosphate and (Sb(B-naphthyl phosphate were substrates with KM of 4.0mM and 8.1mM respectively. PVP showed no reactivity towards phosphoserine. Kinetic characterization of WZB showed that only pnitrophenylphosphate was a substrate with no affinity for Ç-naphthyl phosphate and phosphoserine. Optimal conditions for activity with PNPP were found at a pH of 5 with a KM of 1.1mM, kcat of 35.4s-1 and kcat/KM of 32.2s-1mM-1. Inhibition studies showed that phosphate, fluoride, and molybdate were competitive inhibitors with Ki of 3.2mM, 71.7mM, and 50.4(So(BM respectively and hydrogen peroxide abolished activity. Active site mutants of WZB Cys9Ser and Asp115Asn showed no activity.
Title: Purification and characterization of two members of the protein tyrosine phosphatase family: dual specificity phosphatase PVP and low molecular weight phosphatase WZB.
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Name(s): Livingston, Paula A.
Charles E. Schmidt College of Science
Department of Chemistry and Biochemistry
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Date Issued: 2009
Publisher: Florida Atlantic University
Physical Form: electronic
Extent: x, 92 p. : ill. (some col.)
Language(s): English
Summary: Two protein tyrosine phosphatases, dual specificity phosphatase PVP and low molecular weight phosphatase WZB were purified and characterized. PVP was expressed as inclusion bodies and a suitable purification and refolding method was devised. Enzyme kinetics revealed that p-nitrophenylphosphate and (Sb(B-naphthyl phosphate were substrates with KM of 4.0mM and 8.1mM respectively. PVP showed no reactivity towards phosphoserine. Kinetic characterization of WZB showed that only pnitrophenylphosphate was a substrate with no affinity for Ç-naphthyl phosphate and phosphoserine. Optimal conditions for activity with PNPP were found at a pH of 5 with a KM of 1.1mM, kcat of 35.4s-1 and kcat/KM of 32.2s-1mM-1. Inhibition studies showed that phosphate, fluoride, and molybdate were competitive inhibitors with Ki of 3.2mM, 71.7mM, and 50.4(So(BM respectively and hydrogen peroxide abolished activity. Active site mutants of WZB Cys9Ser and Asp115Asn showed no activity.
Identifier: 465424465 (oclc), 332911 (digitool), FADT332911 (IID), fau:3750 (fedora)
Note(s): by Paula A. Livingston.
Thesis (M.S.)--Florida Atlantic University, 2009.
Includes bibliography.
Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.
Subject(s): Protein-tyrosine phosphatase
Cellular signal transduction
Cell cycle -- Regulation
Membrane proteins -- Structure-activity relationships
Protein kinases
Persistent Link to This Record: http://purl.flvc.org/FAU/332911
Use and Reproduction: http://rightsstatements.org/vocab/InC/1.0/
Host Institution: FAU