Lactose enzymatic analysis

ESI-MS has been used for the quantification of a number of substrates and products of enzymatic reactions [56,57]. Hsieh et al. report the use of ion spray mass spectrometry (a technical variation of electrospray ionization) coupled to HPLC for the kinetic analysis of enzymatic reactions in real time [58]. The hydrolysis of dinucleotides with bovine pancreatic ribonuclease A and the hydrolysis of lactose with 3-galactosidase were monitored and the resulting data were used for the estimation of and v x of these reactions. Another field of application of electrospray mass spectrometry is the screening of combinatorial libraries for potent inhibitors [31,59]. 

In spite of all these difficulties, microdialysis has been successftilly coupled to several analytical techniques for the bioprocess monitoring. HPLC is commonly used and such systems have been apphed in the analysis of oligosaccharides [44,180], ethanol [181], enzymatic digestion of lactose in milk [182], studies on drug dissolution [183], saccharides in wastewater [184], starch hydrolysis products [185]. 

Detection with MS is particularly important for the isolation of compounds that lack useful chromophores or are found only in complicated mixtures such as lactose [56]. The lack of a UV-absorbing chromophore in the saccharide structure limits the mode of detection. Refractive index detection requires precise control of the mobile phase and often does not meet the demands of trace-level analysis needed concerning sensitivity and selectivity. Even chemical derivatization, for example, postcolumn derivatization and enzymatic derivatization, which greatly improves the selectivity and sensitivity of a chromatographic detection systan, does not meet the needed trace levels for the detection of the fine particle dose of lactose. The reason... 

Betschart, H. F. and Prenosil, J. E. 1984. High performance hquid chromatography analysis of the products of enzymatic lactose hydrolysis. J. Chromatogr. 299 498-502. 

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