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In this study, a gene fragment coding carbohydrate-binding module 20 (CBM20) in the amylopullulanase (APU) gene was cloned from the hyperthermophilic bacteria Thermoanaerobacter pseudoethanolicus 39E and expressed in Escherichia coli. The protein, hereafter Tp39E, possesses very low sequence similarity with the CBM20s previously reported and has no starch binding site 2. Tp39E did not demonstrate thermal denaturation at 50 °C; however, thermal unfolding of the protein was observed at 59.5 °C. A binding assay with Tp39E was conducted using various soluble and insoluble substrates, and starch was the best binding polysaccharide. Intriguingly, Tp39E bound, to a lesser extent, to soluble and insoluble xylan as well. The dissociation constant (K d) and the maximum specific binding (B max) of Tp39E to corn starch granules were 0.537 μM and 5.79 μM/g, respectively, at pH 5.5 and 20 °C. 99APU1357 with a Tp39E domain exhibited 2.2-fold greater activity than a CBM20-truncation mutant when starch granules were the substrate. Tp39E was an independently thermostable CBM and had a considerable effect on APU activity in the hydrolysis of insoluble substrates.

An electronic nose-mass spectrometry (EN-MS) that profiles volatile compounds is a candidate device for identifying the geographic origin of cultivation of agricultural products when an adequate algorithm is derived. The objectives of this study were to apply two types of multivariate analysis, discriminant function analysis (DFA) and principal component analysis (PCA), to the volatile compounds detected by an EN-MS for the geographic classification of Chinese cabbage cultivated in Korea (42 samples) or in China (29 samples). DFA showed that Chinese cabbage from Korea were completely separable from those originating in China with 12 volatile compounds among the 151 detected. PCA revealed that Chinese cabbage data fell into two completely separable origins of Korea and China. This is the first study involving EN-MS data of volatile compounds with multivariate statistics to discriminate the geographical origin of Chinese cabbage, with further applications for other agricultural products.