Relative reactivity of phenylboronic acid to phenylboronate ion toward L-lactate and mandelate at physiological pH

• Published in: Inorganic chemistry communications Vol. 13; no. 12; pp. 1406 - 1409
• Main Authors: Watanabe, Eisuke, Fujii, Junko, Kojima, Kaori, Iwatsuki, Satoshi, Inamo, Masahiko, Takagi, Hideo D., Ishihara, Koji
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2010
• Subjects: Kinetics; L-lactic acid; Mandelic acid; Phenylboronic acid; Phenylboronic acid; Mandelic acid; L-lactic acid; Kinetics
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/j.inoche.2010.08.001

Kinetic studies were performed on the reactions of phenylboronic acid with L-lactic acid and mandelic acid in acidic aqueous and alkaline solutions in order to specify reactive species in these reactions. It was confirmed that the diprotonated ligand (H2L: L-lactic acid or mandelic acid) is less reactive than the monoprotonated ligand (HL−: L-lactate ion or mandelate ion), which made possible direct determination of the rate constants of phenylboronic acid (PhB(OH)2) and its conjugate base, phenylboronate ion (PhB(OH)3−). It was found that PhB(OH)2 is more reactive than PhB(OH)3−. On the basis of kinetic results, it was concluded that the most reactive species are PhB(OH)2 and HL− at physiological pH 7.4, so the reaction in the boronic acid-based sensor for L-lactate mainly would occur between these species. Detailed kinetic studies were performed on the reactions of phenylboronic acid with L-lactic acid and mandelic acid in acidic and alkaline solutions, and reactive species were fully specified. [Display omitted]