title: A protease-resistant exo-polygalacturonase from Klebsiella sp. Y1 with good activity and stability over a wide pH range in the digestive tract.
abstract: Polygalacturonases are important feed and food additives. In the present study an exo-polygalacturonase gene (pgu B) was cloned from Klebsiella sp. Y1 CGMCC 4433 and expressed in Escherichia coli BL21 (DE3). pgu B encodes a 658-amino acid polypeptide belonging to Glycoside Hydrolase Family 28. The optimal pH and temperature of exo-PGU B activity were 6.0 and 40-50°C, respectively. The enzyme exhibited >35% of maximum activity within the pH range of 2.0-12.0. Exo-PGU B or an exo-PGU B/ endo-polygalacturonase mixture reduced the viscosity of polygalacturonic acid (1.0%, w/v) by 15.6 and 39.4%, respectively. Under simulated alimentary tract conditions, exo-PGU B was very stable (>25% activity from pH 1.5 to 6.8) and active, releasing 53.7 and 109.6μg of galacturonic acid from 400 to 800μg of polygalacturonic acid, respectively. These properties make exo-PGU B a potentially valuable additive for applications in feed and food.
authors.affiliation: Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China.
authors.forename: Peng
authors.initials: P
authors.lastname: Yuan
authors.forename: Kun
authors.initials: K
authors.lastname: Meng
authors.forename: Yaru
authors.initials: Y
authors.lastname: Wang
authors.forename: Huiying
authors.initials: H
authors.lastname: Luo
authors.forename: Pengjun
authors.initials: P
authors.lastname: Shi
authors.forename: Huoqing
authors.initials: H
authors.lastname: Huang
authors.forename: Yingguo
authors.initials: Y
authors.lastname: Bai
authors.forename: Peilong
authors.initials: P
authors.lastname: Yang
authors.forename: Bin
authors.initials: B
authors.lastname: Yao
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D041981:Gastrointestinal Tract / Q000201:enzymology*; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007709:Klebsiella / Q000201:enzymology*; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014783:Viscosity
chemical_list: D006026:Glycoside Hydrolases; C020136:exopolygalacturonase; D010447:Peptide Hydrolases