Disease relevance of Paranitrophenol

• The polymer-hydrolyzing activity, but not the p-nitrophenylate esterase activity, was inhibited by complex media such as Luria-Bertani medium and by soluble E. coli proteins [1].

High impact information on Paranitrophenol

• Burst experiments at high pH (9.1 or 8.1 for reduced or oxidized PAP, respectively), where hydrolysis of a phosphoenzyme intermediate is expected to be rate-limiting, show clear evidence for stoichiometric bursts of p-nitrophenolate from PNPP [2].
• Previously, the metal complex of the diester methyl-p-nitrophenyl phosphate was found to hydrolyze via a two-step addition-elimination mechanism, in contrast to the concerted hydrolysis mechanism followed by uncomplexed diesters with the p-nitrophenolate leaving group [3].
• In stopped-flow studies using p-nitrophenyl phosphate (pNPP) as a substrate, a burst of p-nitrophenolate in the full length enzyme was not observed; however, a 50-70% stoichiometric burst was observed with the PTPase domain [4].
• 1. p-Nitrophenyl (PNP) acetate and propionate show a burst of p-nitrophenoxide release when their hydrolysis is catalysed by sheep liver cytosolic aldehyde dehydrogenase [5].
• Rapid acetylation of the protein accompanies and largely accounts for the easily observed rapid formation of of p-nitrophenolate ion [6].

Biological context of Paranitrophenol

• The kinetics of p-nitrophenolate formation are directly measured at a wavelength of 410 nm using a spectrophotometer or microtiter plate reader [7].
• The inhibition of the enzyme solubilized in hexadecylphosphocholine micelles was characterized by a rapid (t1/2 = 20 min) and complete loss of enzymatic activity, concurrent with the covalent modification of 50% of the active-site serines, as judged from the amount of p-nitrophenolate (PNP) released [8].

Associations of Paranitrophenol with other chemical compounds

• The three inositols and their intermediate conduritols (conduramines) were tested against several glycosidases (alpha- and beta-glucosidase, alpha- and beta-galactosidase, alpha- and beta-mannosidase) in an assay that measured the rate of hydrolysis of p-nitrophenolglycosides rather than the concentration of p-nitrophenolate [9].
• With PNP dimethylcarbamate the enzyme catalyses the slow release of approx. 1 molecule of p-nitrophenoxide per tetrameric enzyme molecule; during the reaction the enzyme becomes effectively inactivated, as the rate of hydrolysis of the acyl-enzyme is virtually zero [10].
• When the polymerase reactions were performed in the presence of alkaline phosphatase, which digests the p-nitrophenylpyrophosphate side-product of phosphoryl transfer to the chromogenic p-nitrophenylate, an increase in absorbence at 405 nm was observed [11].
• 4. The mitochondrial enzyme shows a low amplitude (22%) burst in the production of 4-nitrophenoxide ion during the hydrolysis of 4-nitrophenyl acetate at pH 7 [12].
• Magnetic circular dichroism (MCD) spectra were observed to characterize the nature of the visible bands for high-spin Fe(III) protoheme derivatives with p-nitrothiophenolate, p-nitrophenolate, and methoxy anion as the fifth ligands in several solvents [13].

Gene context of Paranitrophenol

• Mean basal PTP activities, were found to be significantly higher in diabetics than in normal subjects (type 1 diabetics: 0.36 +/- 0.01 vs 0.28 +/- 0.01 mmol p-nitrophenolate/h per g hemoglobin (Hb), P < 0.001; type 2 diabetics: 0.35 +/- 0.01 vs 0.28 +/- 0.01 mmol p-nitrophenolate/h per g Hb, P < 0.001) [14].
• Non-steady-state kinetic studies reveal that the SN2 reaction between p-nitrophenoxide ion and methyl iodide in acetonitrile containing water follows a 2-step mechanism involving the formation of a kinetically significant intermediate [15].

Analytical, diagnostic and therapeutic context of Paranitrophenol

• An improved assay for N-acetyl-beta-D-glucosaminidase activity in urine is described that involves (a) gel filtration to separate the enzyme from inhibitors in urine, (b) enzymic hydrolysis of p-nitrophenyl-N-acetyl-beta-D-glucosaminide at pH 4.4, and (c) spectrophotometry of the liberated p-nitrophenylate [16].
• During the kinetic study of the destruction process, the determination of remaining concentrations of the alkylating agents was performed by the derivatization of p-nitrophenoxide to p-nitroanisole and p-nitrophenetole, which were separated by high performance liquid chromatography [17].

References