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One-Pot Enzymatic Conversion of Sucrose to Synthetic Amylose by using Enzyme Cascades

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journal contribution
posted on 02.05.2014, 00:00 by Peng Qi, Chun You, Y.-H. Percival Zhang
Synthetic amylose could be a very important compound as a precursor of low-oxygen diffusion biodegradable plastic films, a healthy food additive, and a potential high-density hydrogen carrier. In this study, one-pot reactions composed of sucrose phosphorylase and potato alpha-glucan phosphorylase or supplemented with the three other enzymes (i.e., glucose isomerase, glucose oxidase, and catalase) were carried out to convert cheap sucrose to synthetic amylose, whereas one glucose unit from sucrose was added into the nonreducing end of the primermaltodextrin. A thermostable sucrose phosphorylase was cloned from a thermophilic bacterium Thermoanaerobacterium thermosaccharolyticum JW/SL-YS485. The values of kcat and Km on sucrose were 15.1 s–1 and 20.2 mM, respectively, at 37 °C. The half-life time of this enzyme was 3.1 h at 70 °C. The yield of synthetic amylose was not significantly improved when glucose isomerase, glucose oxidase, and catalase were used to remove fructose, which was an inhibitor to sucrose phosphorylase. This result suggested that the two-enzyme system equipped with the sucrose phosphorylase with a high value of fructose dissociation constant (34.4 mM) did not require the three other enzymes to mitigate product inhibition. The number-average degree of polymerization of synthetic amylose was controlled from 33 to 262 by adjusting primer maltodextrin concentration and reaction time.