Disease relevance of p-nitrophenyl phosphate

• The O157:H7 strain grown at 30 degrees C showed one-sixth the permeability of wild-type E. coli grown at 30 degrees C. Wild-type bacteria grown at >/=37 degrees C show a physiological response with a shift in expression of outer membrane porins that lowered permeability to PNPP by approximately 70% [1].
• A plasma membrane preparation from a human astrocytoma contained p-nitrophenyl phosphate (pNPP), phosphotyrosyl histone, and phosphoseryl histone hydrolysis activities [2].

High impact information on p-nitrophenyl phosphate

• Kinetic analysis of Pyst1 and Pyst1-CD using the substrate p-nitrophenyl phosphate (pNPP) reveals that both molecules undergo catalytic activation in the presence of recombinant inactive ERK2, switching from a low- to high-activity form [3].
• Rate studies show that the enzyme catalyzes the cyclization of the nitrophenylphosphate derivative 47,000,000 times less effectively (kcat/kuncat) than it does uridyladenosine, indicating that approximately 50% of the catalytic free energy change is lost with this substrate [4].
• Using pNPP as substrate, PP6 and PP2A gave the same IC(50) with active site inhibitors okadaic acid, microcystin-LR, calyculin A, and cantharidin [5].
• At increasing concentrations of CaM, the biochemical activity of dual specificity protein phosphatase 1 on the p-nitrophenyl phosphate (pNPP) substrate was increased, whereas activity on the phosphotyrosine of myelin basic protein (MBP) was inhibited [6].
• The hydrolysis of nitrophenylphosphate was used to determine the sedimentation coefficient of the active species [7].

Biological context of p-nitrophenyl phosphate

• In spite of their similarity, apyrase and A-NSAPs show different substrate specificity, apyrase being able to hydrolyse nucleotide tri- and diphosphates, but not monophosphates, as well as p-nitrophenyl phosphate (pNPP), while A-NSAPs are also active towards monophosphates and pNPP [8].
• The hydrolysis of ATP and PNPP by solubilized enzyme exhibited "Michaelian" kinetics with K0.5 = 70 and 979 microM, respectively [9].

Anatomical context of p-nitrophenyl phosphate

• The effects of gangliosides on the hydrolysis of p-nitrophenyl phosphate (pNPP) catalyzed by the erythrocyte plasma membrane Ca(2+)-ATPase, which was characterized as E(2) conformer of the enzyme, were studied [10].
• Monolayers of normal, human glial cells were incubated in situ in an isotonic, buffered sucrose solution (pH 5.0) containing the acid phosphatase (AP) enzyme substrate p-nitrophenyl phosphate (PNPP) [11].
• The acid phosphate activity (APA) associated with the isolated brush border membrane of the tapeworm, Hymenolepis diminuta, hydrolyzed p-nitrophenyl phosphate (PNPP), pyrophosphate (PPi), and beta-glycerophosphate (beta GP) [12].

Associations of p-nitrophenyl phosphate with other chemical compounds

• Labeling with fluorescein isothiocyanate (FITC) largely shifts the Km for p-nitrophenyl phosphate (pNPP) and completely abolishes the stimulation of phosphatase activity induced by erythrosin in the presence of Ca(2+), apparently by FITC impairing dye binding to an activator site and allowing only manifestation of an inhibitory binding site [13].
• Rat osseous plate alkaline phosphatase: effect of neutral protease digestion on the hydrolysis of pyrophosphate and nitrophenylphosphate [14].
• Based upon correlations between enzyme activities, upon reversible inhibition by EDTA and upon progressive inhibition by iso-OMPA, tabun, eserine and bis-4 nitrophenylphosphate, the following conclusions were drawn about the number and specificity of enzymes involved in the hydrolysis [15].
• The localization of reaction product arising from incubation with thiamine pyrophosphate at pH 7.2 and beta-glycerophosphate or nitrophenylphosphate at pH 5 has been examined in central and demilunar acinar cells, myoepithelial cells, and cells of the striated ducts [16].

Gene context of p-nitrophenyl phosphate

• DUSP23 showed distinctive phosphatase activity toward p-nitrophenyl phosphate (pNPP), as well as oligopeptides containing phospho-tyrosine and phospho-threonine residues [17].
• GST-DUSP18 fusion protein showed distinctive phosphatase activity toward p-nitrophenyl phosphate (pNPP), as well as oligopeptides containing pThr and pTyr, indicating that DUSP18 is a protein phosphatase with dual substrate specificity [18].
• A bacterial alkaline phosphatase (BAP, the phoA gene product) is primarily responsible for the hydrolysis of the substrates 5-bromo-4-chloro-3-indolylphosphate-p-toluidine (XP) and p-nitrophenyl phosphate (pNPP) [19].
• The hydrolysis of p-nitrophenyl phosphate (pNPP) catalyzed by calcineurin has been studied by measurement of heavy-atom isotope effects in the substrate [20].
• Deletion of 75 residues (9 kDa) from the C-terminus appeared to have little effect on the catalytic activity using pNPP, phosphopeptides or AMPK as substrates [21].

Analytical, diagnostic and therapeutic context of p-nitrophenyl phosphate

• Dissected tissues were homogenized and Western blot analysis performed, using polyclonal anti-CaN antibodies, and assayed using p-nitrophenyl phosphate (PNPP) as a substrate to determine the dephosphorylation activity of CaN [22].
• The phosphatase has a Mr = 15,000 by gel filtration and exhibits an optimum between pH 5.0 and 6.0 when either Tyr(P)-IgG-casein or PNPP is the substrate [23].
• The competitive ELISA method consists of incubating the coupled bead with a (20/80) weight ratio of goat anti mouse kappa alkaline phosphatase/goat anti mouse kappa (GAMKAP/GAMK) for 1.5 hours at 37 degrees C, washing, adding p-nitrophenyl phosphate (PNPP) substrate, and reading the absorbance at 405/450 nm [24].

References