Simultaneous determination of enzyme activities by FTIR-spectroscopy in an one-step assay Original Research Article

The simultaneous quantification of β-fructofuranosidase (invertase, EC 3.2.1.26) and glucan 1,4-α-glucosidase amyloglucosidase, EC 3.2.1.3) activities in an one-step assay is reported. The approach is based on chemometric evaluation of the mid-IR spectra of the reaction mixture, measured with a sequential injection (SI) system with FTIR spectroscopic detection. Two partial least squares (PLS) calibration models were established automatically. The first model was calculated from reaction mixtures after the action of standard mixtures of both enzymes. The other was built up with mixtures of the substrates (maltose, sucrose) and products (fructose, glucose) without any enzymatic reaction. The establishment of the second model was more rapid as no time for an enzymatic reaction is necessary. Both models gave comparable results for the prediction of mixtures containing 0–2.0 U/ml of each enzyme, with mean errors between 0.08 and 0.05 U/ml.