title: Preferential and rapid degradation of raw rice starch by an α-amylase of glycoside hydrolase subfamily GH13_37.
abstract: The α-amylase (AmyP) from a marine metagenomic library belongs to the recently classified glycoside hydrolase subfamily GH13_37. The degradation abilities of AmyP on a broad range of raw starch granules were examined at 40 °C and pH 7.5. It was found that AmyP is a raw starch-degrading enzyme, exhibiting a unique and remarkable ability to preferentially and very rapidly digest raw rice starch. The specific activity of raw rice starch was reached 118.5 ± 0.6 Umg(-1), which was much higher than that of other raw starches. The final hydrolysis degrees were obtained in 4 h for 1 % raw rice starch and 1 h for 8 % concentration, indicating a very rapid speed of hydrolysis. The presence of a starch residue resistant was the main limiting factor for complete hydrolysis, although end product inhibition also existed, especially at high starch concentrations. AmyP randomly attacks unique or susceptible sites on raw rice starch granules, and releases glucose, maltose, and maltotriose as end products. This is the first biochemical characterization of the raw starch-degrading ability of an α-amylase of family GH13_37. The specific ability towards raw rice starch has never been described before, and this makes AmyP a promising candidate for use as a novel enzyme in rice starch processing.
authors.affiliation: Engineering Technology Research Center of Microorganisms and Biocatalysis, School of Life Sciences, Anhui University, Feixi road 3, Hefei 230039, Anhui, People's Republic of China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Lei
authors.forename: Hui
authors.initials: H
authors.lastname: Peng
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Yuantao
authors.initials: Y
authors.lastname: Liu
authors.forename: Fang
authors.initials: F
authors.lastname: Han
authors.forename: Yazhong
authors.initials: Y
authors.lastname: Xiao
authors.forename: Yi
authors.initials: Y
authors.lastname: Gao
mesh_terms: D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D012275:Oryza / Q000737:chemistry*; D013213:Starch / Q000737:chemistry*; D013379:Substrate Specificity; D013696:Temperature; D000516:alpha-Amylases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D013213:Starch; D006026:Glycoside Hydrolases; D000516:alpha-Amylases