| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 96 === Amadori compounds are formed when a carbonyl group of a sugar reacts with an amine group of an amino group of an amino acid or protein, resulting in an unstable schiff base(imine). After undergoing an Amadori rearrangement, a stable N-substituted(1-deoxy-ketos-1-yl)-amine is formed, this product is called an Amadori compound.
Of all the possible Amadori compounds, many studies now are investigating glycated hemoglobin (HbA1c), which is a significant biomarker for diabetes patients. When compared with the dynamic fluctuation of blood sugar concentrations, HbA1c serves as a long-term indicator (2-3 months). Erythrocytes are freely permeable to glucoses, which can react with the N-terminal valine of the β-chain of hemoglobin, to form the Amadori compound. As a result, the terminal valine becomes a N-(1-deoxy-β-D-fructopyranose-1-yl)-L-valine (Fru-Val).
The model compound in this study was Fru-Val, which was synthesized as in a previous paper. The purity and structure were checked by infrared spectroscopy, elemental analysis and nuclear magnetic resonance spectroscopy respectively. Further , the mass was checked by mass spectroscopy.
The cyclic voltammograms(CVs) carried out at different pH values showed the anodic oxidation of Fru-Val is a pH dependent reaction. The CVs reveal that under basic conditions, by OH- exchange, Fru-Val is in equilibrium with its eneaminol tautomer ; however, competing with this reaction at potentials in the range 1.0 to 1.2V is the hydrolysis of water, thereby rendering determination of a limiting current difficult.
An approach to determining the net current of Fru-Val(10mM) in pH10 buffer has been made by subtracting currents determined in pH10 buffer from those made in a similar solution but additionally containing 10mM Fru-Val. The result of this is a CV profile in which the net current declines at an potential greater than 1.15V.
Interestingly, an 3-aminophenyl boronic acid polymer, molecularly imprinted with Fru-Val, showed a step-wise change in response to 10 mM D-fructose additions. A similar polymer was able to demonstrate a significantly greater response to D-fructose than to D-glucose; thereby indicating that the fructose part of Fru-Val molecule had been successfully imprinted and was able to show recognition for the D-fructose part of the Fru-Val imprinting template.
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