A Simple Preparation of PEG‐Carboxylates by Direct Oxidation

Фишман, А. И.; Acton, Austin; Lee‐Ruff, Edward

doi:10.1081/scc-120038518

Cited by 24 publications

(19 citation statements)

References 3 publications

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“…The following synthesis was a modified combination of methods used by Fishman et al [20] for the simple preparation of PEG-carboxylates by direct oxidation, Johansson et al [21] for the synthesis of a polymer used in affinity partitioning of synaptic membrane domains, and Conroy et al [14] for covalent linkage reagents. Polyethylene glycol (5.00 g, 1.49 mmol) and H 2 SO 4 (32 mL) were dissolved in 100 mL of deionized water and cooled in an ice-water bath.…”

Section: Methodsmentioning

confidence: 99%

Detecting extracellular carbonic anhydrase activity using membrane inlet mass spectrometry

Delacruz

Mikulski

et al. 2010

Analytical Biochemistry

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Current research into the function of carbonic anhydrases in cell physiology emphasizes the role of membrane-bound carbonic anhydrases, such as carbonic anhydrase IX that has been identified in malignant tumors and is associated with extracellular acidification as a response to hypoxia. We present here a mass spectrometric method to determine the extent to which total carbonic anhydrase activity is due to extracellular carbonic anhydrase in whole cell preparations. The method is based on the biphasic rate of depletion of 18 O from CO 2 measured by membrane inlet mass spectrometry. The slopes of the biphasic depletion are a sensitive measure of the presence of carbonic anhydrase outside and inside of the cells. This property is demonstrated here using suspensions of human red cells in which external carbonic anhydrase was added to the suspending solution. It is also applied to breast and prostate cancer cells which both express exofacial carbonic anhydrase IX. Inhibition of external carbonic anhydrase is achieved by use of a membrane impermeant inhibitor that was synthesized for this purpose, p-aminomethylbenzenesulfonamide attached to a polyethyleneglycol polymer.Keywords carbonic anhydrase; mass spectrometry; carbon dioxide; stable isotope; enzyme activityThe zinc metalloenzyme carbonic anhydrase (CA) catalyzes the hydration of carbon dioxide to form bicarbonate and a proton [1,2]. There are 16 isozymes of CA in the α-class of mammalian carbonic anhydrases that play a role in respiration, formation of secretory fluids, acid-base balance, and other physiological functions [3]. The isozyme CA IX is of particular interest since it is found in few normal tissues but its expression is induced in certain tumor cells by hypoxia [4,5]. CA IX is a transmembrane protein the catalytic site of which is external to the cell and is shown to play a role in extracellular acidification associated with cell Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. proliferation and metastasis [6][7][8][9]. Its inhibition may be of benefit in anticancer therapies for several types of cancer, including breast and prostate cancer. NIH Public AccessThe inhibition of carbonic anhydrases by sulfonamides is well studied in terms of its biochemical, physiological, and medical aspects [3,10,11]. Oxygen-18 and carbon-13 labeled bicarbonate was prepared by dissolving KH 13 CO 3 (99% 13 C) in enriched water (up to 90% 18 O enrichment). This solution was allowed to come to isotopic equilibrium overnight, after which water was removed by vacuum distillation. The resulting product was stored at room temp...

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Section: Methodsmentioning

confidence: 99%

Detecting extracellular carbonic anhydrase activity using membrane inlet mass spectrometry

Delacruz

Mikulski

et al. 2010

Analytical Biochemistry

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“…CDCl 3 used as solvents in the NMR measurements was obtained from Aldrich Corporation. [26,27] MPEG (2.5 g, 0.5 mmol) was dissolved in 25 ml of deionized (DI) water containing 8 ml of H 2 SO 4 (95e98%) in a 100 ml round bottom flask; added a solution of CrO 3 (0.33 g, 3.3 mmol, in 5 ml water) to the mixture, and stirred it for 12 h at room temperature. Then 25 ml water was added to the solution and the mixture was stirred for 1 h. To purify the product, we used CH 2 Cl 2 (3 Â 100 ml) to extract the PEG-carboxylates and washed the organic layer by water (2 Â 25 ml) and saturated NaCl solution (2 Â 25 ml), successively.…”

Section: Methodsmentioning

confidence: 99%

Force spectrum of a few chains grafted on an AFM tip: Comparison of the experiment to a self-consistent mean field theory simulation

Wang

Qiu

et al. 2007

Polymer

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“…Vibrational bands at 1701 and 1734 cm − 1 were found. The latter could be attributed to 1) the terminal PEG hydroxy group, which is oxidized to a carboxyl group in the acid reaction media [26,27] (in silica/PEG materials it appeared as a band at 1742 cm −1 ), and 2) the esterification reaction of this PEG group with quercetin phenolic functions on the basis of which the red shift was observed [24]. The displacement of the quercetin C_O stretch by about 40 cm − 1 (1701 cm − 1 ) could be due to the predominance of the quercetin Cring diketo-form, whose presence was also suggested by the disappearance of the characteristic absorption of the C 2 -C 3 double bond at 1610 cm −1 .…”

Section: Characterization Of the Synthesized Materialsmentioning

confidence: 98%

Entrapping quercetin in silica/polyethylene glycol hybrid materials: Chemical characterization and biocompatibility

Catauro

Bollino

Nocera

et al. 2016

Materials Science and Engineering: C

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A Simple Preparation of PEG‐Carboxylates by Direct Oxidation

Cited by 24 publications

References 3 publications

Detecting extracellular carbonic anhydrase activity using membrane inlet mass spectrometry

Detecting extracellular carbonic anhydrase activity using membrane inlet mass spectrometry

Force spectrum of a few chains grafted on an AFM tip: Comparison of the experiment to a self-consistent mean field theory simulation

Entrapping quercetin in silica/polyethylene glycol hybrid materials: Chemical characterization and biocompatibility

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