Colorimetric method for rare sugars to distinguish aldoses and ketoses and its application
2019
Morimoto, K. | Suzuki, T.
A rapid screening method of ketose 3-epimerase, SiMo method, was developed using Si (IV)-Mo (VI) solution. This solution is a yellow color without ketoses. Ketoses except psicose (allulose) was rapidly formed blue 12-molybdosilicate anionic species by Si (IV)-Mo (VI) under acidic pH. Although cysteine-carbazole method, which was specifically detected ketose, shows same level coloration for various ketoses, colorization by Si (IV)-Mo (VI) was different depending on the species of ketoses. By contrast, the formation rate of 12-molybdosilicate anionic species for almost aldoses was very slow. The candidates possessing ketose 3-epimerase activity was screened from various samples. This activity was detected the formation of D-fructose from D-psicose using SiMo method. Positive control such as Shinella sp. NN-6 and recombinant D-tagatose 3-epimerase was detected enzymatic activity using this method. No activity was detected by screened samples in this study, suggesting that positive colonies were not detected in SiMo method due to low detection sensitivity.
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