Title
Spectrophotometric tool for the determination of the total carboxylate content in proteins; molar extinction coefficient of the enol ester from Woodward's reagent K reacted with protein carboxylates
Author
Kosters, H.A.
de Jongh, H.H.J.
TNO Voeding
Publication year
2003
Abstract
A number of relevant properties of Woodward's reagent K have been determined, such as the stability of the reactant and the optimal reaction conditions of the reactant with protein carboxylates. A Woodward's reagent K stock solution was stable at 4°C for prolonged time, whereas upon storage at 22°C, almost 20% of the reactive compound was lost within 1 week. The pH-dependency of the spontaneous degradation reaction of Woodward's reagent K was studied and was shown to be basemediated. A molar extinction coefficient of 3150 M-1 cm-1 at 269 nm for the enol ester resulting from the reaction between Woodward's reagent K and the protein carboxylates was established using the conditions laid out in this work. This value was validated using a variety of proteins that were modified by Woodward's reagent K. In addition, upon methylation of the carboxylates of a single protein, ovalbumin in this case, the degree of modification could be determined accurately and was confirmed by cation exchange chromatography elution profiles. Chemicals/CAS: ovalbumin, 77466-29-6; Carboxylic Acids; Esters; Isoxazoles; N-ethyl-5-phenylisoxazolium-3'-sulfonate, 4156-16-5; Ovalbumin, 9006-59-1; Proteins
Subject
Nutrition
Food technology
Chemical modification
Chromatographic analysis
Degradation
Esters
pH effects
Spectrophotometry
Molar extinction
Proteins
chemical analysis
degradation
ion exchange chromatography
methylation
molecular stability
pH
protein modification
protein stability
reaction analysis
spectrophotometry
temperature dependence
validation process
Animals
Carboxylic Acids
Chickens
Esters
Isoxazoles
Kinetics
Ovalbumin
Proteins
Spectrophotometry, Ultraviolet
To reference this document use:
http://resolver.tudelft.nl/uuid:af22850a-273d-47db-9db4-a9066939986f
DOI
https://doi.org/10.1021/ac026279e
TNO identifier
237087
ISSN
0003-2700
Source
Analytical Chemistry, 75 (10), 2512-2516
Document type
article