Calcium complexing behaviour of lactate in neutral to highly alkaline medium

Publication date: Available online 7 December 2018Source: Journal of Molecular StructureAuthor(s): Csilla Dudás, Bence Kutus, Éva Böszörményi, Gábor Peintler, Amr A.A. Attia, Alexandru Lupan, Zoltán Kele, Pál Sipos, István PálinkóAbstractThe calcium complexing properties as well as the acid-base behaviour of d,l-lactate have been investigated in both neutral and alkaline media by Ca-ISE potentiometry, 13C NMR spectroscopy, ESI-MS spectroscopy and solubility measurements. In close to neutral solutions the formation of the CaLac+ and CaLac20 complexes were detected with formation constants of logK1,1 = 0.99 ± 0.02 and logβ1,2 = 1.42 ± 0.03 (I = 4 M, T = 25 °C). These data are consistent with previously reported literature data measured at lower ionic strengths. The alkaline deprotonation constant of lactate has been determined to be pKa = 15.8 ± 0.2. In highly alkaline medium, the formation of the CaLacOH0 and CaLac(OH)2– complexes were detected with the corresponding formation constants being logβ1,1,1 = 1.35 ± 0.09 and logβ1,1,2 = 1.43 ± 0.06. The structures of the CaLac+ and CaLacOH0 complexes were optimized by molecular modelling calculations.Graphical abstract

Source: Journal of Molecular Structure - December 9, 2018 Category: Molecular Biology Source Type: research