Ultrasonic Monitoring of Enzyme Catalysis; Enzyme Activity in Formulations for Lactose-Intolerant Infants

Abstract

The paper introduces ultrasonic technology for real-time, nondestructive, precision monitoring of enzyme-catalyzed reactions in solutions and in complex opaque media. The capabilities of the technology are examined in a comprehensive analysis of the effects of a variety of diverse factors on the performance of enzyme β-galactosidase in formulations for reduction of levels of lactose in infant milks. These formulations are added to infant's milk bottles prior to feeding to overcome the frequently observed intolerance to lactose (a milk sugar), a serious issue in healthy development of infants. The results highlight important impediments in the development of these formulations and also illustrate the capability of the described ultrasonic tools in the assessment of the performance of enzymes in complex reaction media and in various environmental conditions.

Ultrasonic Monitoring of Biocatalysis in Solutions and Complex Dispersions

“…Concentration increment of ultrasonic velocity of hydrolysis, ∆a r was calculated using Equation (6). The linear dependence of ∆a r on c L (triangles) was extrapolated to c L = 0 to account for minor effects of lactose present in milk prior addition of reactants and products producing ∆a r = (0.0147 ± 0.0004) kg/mol [8]. Adapted with permission from Reference [8] Copyright © 2016 American Chemical Society.…”

“…The linear fit parameters were obtained by fitting of the dependence of 2 2 H O a on concentration of H2O2, which provides slightly better extrapolation of 2 2 H O a to infinite dilution than the direct fitting of ultrasonic velocity vs. concentration utilized in [5]. Red diamonds: hydrolysis of lactose in infant milk and in water [8]. Blue circles: hydrolysis of lactose in water [8].…”

“…Red diamonds: hydrolysis of lactose in infant milk and in water [8]. Blue circles: hydrolysis of lactose in water [8]. Green triangles: decomposition of hydrogen peroxide in water at infinite dilution (calculated from plots (B)).…”

“…Red diamonds: hydrolysis of lactose in infant milk and in water [8]. Blue circles: hydrolysis of lactose in water [8].…”

“…In general, these techniques have a limited dynamic (concentration) range. In addition, UV-Vis and fluorescence spectroscopies require an optical activity of the reactants or products and, in their absence, the analysis is more complicated as chromogenic and fluorogenic substrates are needed [8][9][10]. Therefore, discontinuous methods are widely used for the monitoring of chemical reactions, including chromatography, mass spectrometry (MS) and capillary electrophoresis [9].…”