Pyranose Oxidases

Pyranose oxidase (PYROX, EC; see Refs. 55-57, 59 for more detailed information) catalyzes the oxidation of several monosaccharides at the C2-position and is therefore different from GOX, which oxidizes glucose at the C1-position. While GOX is very specific, PYROX is able to catalyze other substrates such as maltose and pentoses (e.g., xylose). As a result, the PYROX oxidation product of glucose is 2-keto-glucose and not gluconic acid. At present, this enzyme has been purified from several white rot fungi and a Bacidiomycetous fungus (55-57). PYROX has also been reported to show significant activity toward D-glucono-1,5-lactone, which is produced by the GOX-catalyzed oxidation of glucose (58). So if PYROX is combined with GOX, there will be more substrate available for PYROX, thereby prolonging the activity of PYROX and enhancing the total amount of hydrogen peroxide produced (59). The claimed effects in baking are gluten strengthening, reduced dough stickiness, and increased volume and crumb structure for bread (59).

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