Synthesis and Characterization of Pyridine Compounds for Amperometric Measurements of Leukocyte Esterase |
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Authors: | Douglas Hanson Travis Menard Teresa Blazek Prof. Dr. Stanton McHardy Prof. Dr. Waldemar Gorski |
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Affiliation: | Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, USA |
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Abstract: | We introduce a new class of substrates (compounds I – III ) for leukocyte esterase (LE) that react with LE yielding anodic current in direct proportion to LE activity. The kinetic constants Km and kcat for the enzymatic reactions were determined by amperometry at a glassy carbon electrode. The binding affinity of I – III for LE was two orders of magnitude better than that of existing optical LE substrates. The specificity constant kcat/Km was equal to 2.7, 3.8, and 5.8×105 m ?1 s?1 for compounds containing the pyridine ( I ), methoxypyridine ( II ), and (methoxycarbonyl)pyridine ( III ), respectively, thus showing an increase in catalytic efficiency in this order. Compound III had the lowest octanol/water partition coefficient (log p=0.33) along with the highest topological surface area (tPSA=222 Å2) and the best aqueous solubility (4.0 mg mL?1). The average enzymatic activity of LE released from a single leukocyte was equal to 4.5 nU when measured with compound III . |
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Keywords: | catalysis electrochemistry esterases leukocytes synthesis |
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