Endo-beta-glucanase secreted by a psychrotrophic yeast: purification and characterization.
A psychrotrophic yeast, Rhodotorula glutinis KUJ 2731, isolated from soil, effectively produced an extracellular endo-beta-glucanase (EC 3.2.1.4). The enzyme was monomeric, and the molecular mass was about 40,000 Da. The N-terminal amino acid sequence was H-Ser-Leu-Pro- Lys-Leu-Gly-Gly-Val-Asp-Leu-Ala-Gly-Leu-Asp-Ile-Gly-Lys-Asp-Lys-Asn-. alpha-Helix content was calculated to be about 32.6%. The isoelectric point was 8.57. The activation energy was 20.9 kJ/mol, which was much smaller than that of mesophilic enzymes. The enzyme was active at temperatures from 0 to 70 degrees C, with a highest initial velocity at 50 degrees C similar to other psychrotrophic enzymes. The enzyme was inhibited by Hg2+. The enzyme catalyzed hydrolysis of carboxymethyl cellulose with an apparent K(m) of 1.1% and Vmax of 556 mumol/min/mg. Products from the enzymatic hydrolysis of carboxymethyl cellulose by the enzyme were glucose, cellobiose, and cellotriose. The enzyme also catalyzed the transglycosylation of p-nitrophenyl-beta-cellotrioside to cellotetraose.
Oikawa
T
T
Department of Biotechnology, Faculty of Engineering, Kansai University, Osaka, Japan. oikawa@ipcku.kansai-u.ac.jp
Tsukagawa
Y
Y
Soda
K
K
D000595:Amino Acid Sequence; D002480:Cellulase / Q000302:isolation & purification / Q000378:metabolism*; D006031:Glycosylation; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007526:Isoelectric Point; D008670:Metals; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009844:Oligosaccharides / Q000378:metabolism; D012248:Rhodotorula / Q000201:enzymology*; D013057:Spectrum Analysis; D013696:Temperature
D007477:Ions; D008670:Metals; D009844:Oligosaccharides; D002480:Cellulase