Mutarotase assay

Figure 5. Mutarotase assay by the GLC-TMSi method. The enzyme preparation was obtained from hog kidney, and the conditions are those described previously (26).

The oxidation reactions of luminol and lucigenin can be used to assay for H Oj. For example, analysis of glucose in biological systems can be achieved using a three-enzyme system of mutarotase, glucose oxidase and horseradish peroxidase by correlation with the amount of HjOj released. Similarly, cholesterol can be measured using cholesterol oxidase. The fact that the rate of luminol oxidation depends on the concentration of the catalyst can be used as a method for determination of Co +, Fe +, Cr + and Mn + and other catalysts.Some examples of the use of luminol, isolumi-nol and their derivatives in immunoassays are shown in Table 3.11. ... 

The majority of the many methods used to study the composition of equilibrium solutions of carbohydrates examine the mixture without separating the individual components. With the discovery that the anomeric forms of sugars could be readily separated by gas chromatography of their tri-methylsilyl ethers, a new approach to the problem was found. A protocol was developed for the direct gas chromatographic analysis of the amount of each anomer present in an aqueous solution. The protocol can be used on the micro scale and can be used in enzyme assays such as that for mutarotase. The method has been made more effective by combining gas chromatography with mass spectrometry. It is shown how mass spectral intensity ratios can be used to discriminate anomers one from another. The application of these methods to the study of complex mutarotations is discussed. 

The detection scheme based on maltose phosphorylase, mutarotase and glucose oxidase with chemiluminescence detection and implemented into an FIA system has been thoroughly investigated on freshwater samples [264]. Interferences were eliminated with a cation-exchange resin as the only sample pretreatment and the results of 31 river and pond waters correlate fairly well with the molybdenum assay (r = 0.96) [264]. A laboratory based multichannel FIA equipment has the enz5mies immobihzed in a packed bed... 

The coupled reactions of isomerase, mutarotase and GOD should be applicable to assay fructose, but a sensor using this sequence has not been described to date. An FIA manifold containing an enzyme reactor with glucose isomerase and mutarotase for the determination of fructose has been developed by Olsson (1987). The glucose formed was measured spectrophotometrically. 

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