Related Experiment Video
Updated: Aug 1, 2026

A Rapid and Specific Microplate Assay for the Determination of Intra- and Extracellular Ascorbate in Cultured Cells
Published on: April 12, 2014
Effect of albumin on the kinetics of ascorbate oxidation
E Lozinsky1, A Novoselsky, A I Shames
1Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel. lozinsky@bgumail.bgu.ac.il
Abstract:
The fluorescence intensity of the fluorophore in dansyl piperidine-nitroxide is intramolecularly quenched by the nitroxyl fragment. Therefore, the oxidation of ascorbic acid by the fluorophore-nitroxide (FN) probe can be monitored by two independent methods: steady-state fluorescence and electron paramagnetic resonance. Bovine serum albumin (BSA) affects the rate of this reaction. The influence of BSA on the rate is attributed to the adsorption of both ascorbate and the probe to BSA. Adsorption of ascorbate to BSA is confirmed by NMR relaxation experiments. The spatial distribution of the molecules on the BSA surface changes the availability of ascorbate and FN to each other. The results also point out that, in the presence of BSA, the autoxidation of ascorbate is significantly slowed down. The effect is studied at different pH values and explained in terms of the electrostatic interaction between the ascorbate anion and the BSA molecule.
Related Concept Videos
Polyprotic Acids
Oxidation of Phenols to Quinones
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
Factors Affecting Protein-Drug Binding: Protein-Related Factors
The physicochemical properties of a drug play a significant role in its ability to bind to proteins. Lipophilic drugs, which dissolve in fats, oils, and lipids, can be bound by...
Factors Affecting Protein-Drug Binding: Patient-Related Factors
Age stands as a key determinant in protein-drug binding. Neonates, characterized by low albumin content, experience heightened concentrations of unbound drugs such as phenytoin and...
Hepatic Drug Clearance: Effect of Protein Binding
For low-extraction-ratio drugs that are less than 80% protein-bound, minor changes in protein binding...
Nonlinear Pharmacokinetics: Bioavailability and Protein-Drug Binding
To quantify the extent of bioavailability, pharmacologists often use a parameter called .

