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3 results on '"Serge Kokot"'

1. Effects of aluminum on amyloid-beta aggregation in the context of Alzheimer’s disease

Author

Qiulan Zhang, Fangyuan Zhang, Yongnian Ni, and Serge Kokot

Subjects
Chemistry, QD1-999
Abstract

Alzheimer’s disease (AD) is one of the most common age-associated pathologies, which inevitably leads to dementia and death. The aggregation of β-amyloid (Aβ) peptides on plaques in brain tissue is strongly associated with AD. The possible link between aluminum and AD still remains controversial. In this work, the aggregation of Aβ40 induced by Al(III) was investigated with the use of the fluorescence quenching method, UV–visible and circular dichroism spectroscopies as well as the atomic force microscopy technique. The results demonstrated that Al(III) induced the transformation of the initial random coil structure to the β-sheet configuration in the Aβ40 peptides. These structural changes facilitated the aggregation of Aβ40. Also, the binding constant was calculated with the use of the multivariate curve resolution-alternating least squares (MCR-ALS) chemometrics method. Keywords: Alzheimer’s disease, β-Amyloid peptides, Spectroscopy, Chemometrics

Published
2019
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2. Interaction Between Quercetin-Copper (II) Complex and DNA With the Use of the Neutral Red Dye Fluorophor Probe

Author

Shan Du, Serge Kokot, and Yongnian Ni

Subjects
Absorption spectroscopy, Quercetin-Cu(II) Complex, DNA, Neutral Red Dye Fluorescence Probe, Intercalation, Alternative Least Squares, Intercalation (chemistry), Fluorescence spectrometry, Analytical chemistry, Biochemistry, Analytical Chemistry, Spectrophotometry, Electrochemistry, medicine, Animals, Environmental Chemistry, Molecule, Least-Squares Analysis, Spectroscopy, Equilibrium constant, Fluorescent Dyes, 030499 Medicinal and Biomolecular Chemistry not elsewhere classified, medicine.diagnostic_test, Chemistry, DNA, Binding constant, 030106 Quality Assurance Chemometrics Traceability and Metrological Chemistry, Crystallography, Neutral Red, 030100 ANALYTICAL CHEMISTRY, Cattle, Quercetin, 060101 Analytical Biochemistry, Cyclic voltammetry, Copper
Abstract

The interaction of quercetin-Cu(II) complex with calf thymus DNA was investigated with the use of Neutral Red (NR) dye as a spectral probe by the application of UV-vis spectrophotometry, cyclic voltammetry and synchronous fluorescence spectroscopy. The results showed that both quercetin-Cu(II) complex and the NR molecule can intercalate into the double helix of the DNA. The 2:1 quercetin:Cu(II) complex (estimated binding constant = 2.85 x 10(9)) is stabilized by intercalation in the DNA (binding constant, K[quercetin-Cu(II)-DNA] = (1.82 +/- 0.20) x 10(5) M-1), and displaces the NR dye from the NR-DNA complex in a competitive reaction. Cyclic voltammetry studies confirm the intercalation reaction and show that the ratio (K-R/K-O) of binding constants for the reduced and oxidized forms of the metal complex is 2.05. Furthermore, the alternative least squares (ALS) method was applied to resolve a complex two-way array of the absorption spectra data. This yielded the equilibrium concentration profiles of each component in the reaction (NR, NR-DNA and quercetin-Cu(II)) as well as the corresponding pure spectra. The extracted profiles showed that at equilibrium the [NR-DNA] and [NR] trends decreased and increased symmetrically, respectively, with approximately linear behaviour being observed below 10 x 10(-6) mol L-1 of the added quercetin-Cu2+ complex. Thereafter, these trends converged asymptotically. The free [quercetin-Cu(II)] trend-line at equilibrium was linear over the whole range of the complex added. It was possible to estimate the approximate value of the equilibrium constant of the exchange process (approximately 5 x 10(-1)) involving the intercalation of the quercetin-Cu(II) complex. It was also found that about 35% of the bound complex was unaccounted by the intercalation reaction, presumably being stabilized at an alternative site. (c) 2006 Elsevier B.V. All rights reserved.

Published
2007

3. CHEMOMETRICS AND STATISTICS | Multicriteria Decision Making

Author

Godwin A. Ayoko and Serge Kokot

Subjects
Multicriteria decision, Chemometrics, Computer science, business.industry, Pattern recognition (psychology), Artificial intelligence, Machine learning, computer.software_genre, business, computer
Abstract

The name ‘chemometrics’ was first used by Svante Wold in a Swedish journal. In general, it refers to a chemical discipline that focuses on maximizing the extraction of information from data and experimental measurements with the aid of mathematical, computational, and logic methods. The data or information collected are submitted for analysis by one or more methods of chemometrics typically associated with pattern recognition, classification, or prediction.

Published
2005

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