title: Expression and Characterization of Levansucrase from Clostridium acetobutylicum.
abstract: The Clostridium acetobutylicum gene Ca-SacB encoding levansucrase was cloned and expressed in Escherichia coli. Ca-SacB is composed of 1287 bp and encodes 428 amino acid residues, which could convert 150 mmol/L sucrose to levan with the liberation of glucose. The optimum pH and temperature of this enzyme for levan formation were pH 6 and 60 °C, respectively. Levansucrase activity of Ca-SacB was completely abolished by 5 mmol/L Ag+and Hg2+. The Kmand Vmaxvalues for levansucrase were calculated to be 64 mmol/L and 190 μmol/min/mg, respectively. Interestingly, Ca-SacB was found to have high product specificity, and no fructooligosaccharide was identified in the product, indicating that Ca-SacB may be valuable for industrial production of levan. In addition, Ca-SacB is the first characterized levansucrase isolated from an anaerobic bacterium, which should be valuable for exploring new enzyme resources and deepening the understanding of the catalytic mechanisms of levansucrases.
authors.forename: Song
authors.initials: S
authors.lastname: Gao
authors.affiliation: School of Food and Biological Engineering, Jiangsu University , Zhenjiang 212000, China.
authors.forename: Xianghui
authors.initials: X
authors.lastname: Qi
authors.affiliation: Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes , Grenoble 38044, France.
authors.forename: Darren J
authors.initials: DJ
authors.lastname: Hart
authors.forename: Herui
authors.initials: H
authors.lastname: Gao
authors.forename: Yingfeng
authors.identifier: http://orcid.org/0000-0002-4006-4602
authors.initials: Y
authors.lastname: An
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D046969:Clostridium acetobutylicum / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005630:Fructans / Q000378:metabolism; D006602:Hexosyltransferases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D009844:Oligosaccharides / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005630:Fructans; D009844:Oligosaccharides; C116580:fructooligosaccharide; D013395:Sucrose; C072599:levan; D006602:Hexosyltransferases; C021513:levansucrase
keywords: Ca-SacB; Clostridium acetobutylicum; levan; levansucrase