The Ionization Constants of Calcium Proteinate Determined by the Solubility of Calcium Carbonate

Weir, Everett G.; Hastings, A. Baird

doi:10.1016/s0021-9258(18)74811-4

Cited by 35 publications

(1 citation statement)

References 8 publications

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“…As opposed to the solid protein-based biosensor not detecting the prooxidant activities of RA and RES compounds, the corresponding values were perfectly determined by the proposed biosensor. Furthermore, CEW was firmly held by gold NPs (due to protein−thiol bonding to gold) forming a stable sensor while the Ca-proteinate solid had a relatively high ionization constant 49 causing partial leachability of sensor constituents. The developed biosensor was durable, reliable, less expensive, easily applicable, and gave highly reproducible results in reporting the prooxidant activities of antioxidant compounds and herbal extracts.…”

Section: Discussionmentioning

confidence: 99%

Protein-Protected Gold Nanocluster-Based Biosensor for Determining the Prooxidant Activity of Natural Antioxidant Compounds

et al. 2019

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In this work, chicken egg white protein (CEW)-protected gold nanoclusters (CEW-AuNCs) were prepared from CEW and HAuCl 4 to measure the Cu(II)-induced prooxidant activity of antioxidant compounds such as epicatechin, epigallocatechin gallate, catechin, rosmarinic acid, resveratrol, ascorbic acid, and glutathione. These compounds reduced Cu(II) to Cu(I), and the latter was mainly bound to thiol groups in the CEW-AuNC structure. As the protein-bound Cu(I) may act as a catalytic center for generating reactive oxygen species, the Cu(II) reducing ability of antioxidants is an indirect measure of their prooxidant potency. The bound Cu(I) may be released with the cuprous-selective ligand neocuproine (Nc), forming the basis of a spectrophotometric method measuring absorbance at 450 nm wavelength of the Cu(I)–Nc chelate. The developed method involved a one-pot synthesis and determination without preseparation and was applied to binary synthetic mixtures of studied antioxidant compounds and to certain herbal plant (green tea, linden, echinacea, and artichoke leaf) extracts to determine the total prooxidant activities. The obtained results were statistically compared with those of the literature Cu(II)–Nc assay using a calcium proteinate-based solid biosensor. The developed biosensor was durable, reliable, easily applicable, and of low cost and wide linear range and could determine the prooxidant activities of natural antioxidant samples with high reproducibility.

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Section: Discussionmentioning

confidence: 99%