title: Partial purification and characterization of an enzyme from pea nuclei with protein tyrosine phosphatase activity.
abstract: A pea (Pisum sativum L.) nuclear enzyme with protein tyrosine phosphatase activity has been partially purified and characterized. The enzyme has a molecular mass of 90 kD as judged by molecular sieve column chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Like animal protein tyrosine phosphatases it can be inhibited by low concentrations of molybdate and vanadate. It is also inhibited by heparin and spermine but not by either the acid phosphatase inhibitors citrate and tartrate or the protein serine/threonine phosphatase inhibitor okadaic acid. The enzyme does not require Ca2+, Mg2+, or Mn2+ for its activity but is stimulated by ethylenediaminetetraacetate and by ethyleneglycolbis(beta-aminoethyl ether)-N,N'-tetraacetic acid. It dephosphorylates phosphotyrosine residues on the four different 32P-tyrosine-labeled peptides tested but not the phosphoserine/threonine residues on casein and histone. Like some animal protein tyrosine phosphatases, it has a variable pH optimum depending on the substrate used: the optimum is 5.5 when the substrate is [32P]tyrosine-labeled lysozyme, but it is 7.0 when the substrate is [32P]tyrosine-labeled poly(glutamic acid, tyrosine). It has a Km of 4 microM when the lysozyme protein is used as a substrate.
authors.affiliation: Department of Botany, The University of Texas at Austin 78713, USA.
authors.forename: Y L
authors.initials: YL
authors.lastname: Guo
authors.forename: S J
authors.initials: SJ
authors.lastname: Roux
mesh_terms: D002122:Calcium Chloride / Q000494:pharmacology; D002467:Cell Nucleus / Q000201:enzymology*; D002614:Chelating Agents / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D019343:Citric Acid / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006493:Heparin / Q000494:pharmacology; D015636:Magnesium Chloride / Q000494:pharmacology; D017895:Manganese Compounds / Q000494:pharmacology; D008982:Molybdenum / Q000494:pharmacology; D019319:Okadaic Acid / Q000494:pharmacology; D018532:Pisum sativum / Q000737:chemistry / Q000166:cytology* / Q000201:enzymology* / Q000378:metabolism; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000302:isolation & purification* / Q000378:metabolism*; D012969:Sodium Fluoride / Q000494:pharmacology; D013096:Spermine / Q000494:pharmacology; D013644:Tartrates / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology; D017967:Zinc Compounds / Q000494:pharmacology
chemical_list: D002614:Chelating Agents; D002712:Chlorides; D004791:Enzyme Inhibitors; D017895:Manganese Compounds; D013644:Tartrates; D017967:Zinc Compounds; D015636:Magnesium Chloride; C044659:molybdate; D019319:Okadaic Acid; D019343:Citric Acid; D013096:Spermine; D014638:Vanadates; D004533:Egtazic Acid; D008982:Molybdenum; C016837:zinc chloride; D012969:Sodium Fluoride; D006493:Heparin; D004492:Edetic Acid; D017027:Protein Tyrosine Phosphatases; D002122:Calcium Chloride; C025340:manganese chloride; C029768:tartaric acid