Purification and characterization of novel glucanases from Trichoderma harzianum ETS 323.
Trichoderma harzianum ETS 323 secretes two glucanases, a 23.5 kDa endoglucanase (EG Th1) and a 61 kDa exoglucanase (ExG Th1). They were identified by their hydrolysis products and were purified to homogeneity. The optimal temperature and pH for both EG Th1 (7.3-fold purification, 5.0% yield) and ExG Th1 (33.7-fold purification, 0.15% yield) were 50 °C and pH 4.5, respectively. The kinetic parameters of EG Th1 (K(m) = 23 mg mL(-1), V(max) = 294 μM min(-1), specific activity = 7.4 U mg(-1)) and ExG Th1 (K(m) = 85 mg mL(-1), V(max) = 385 μM min(-1), specific activity = 24.6 U mg(-1)) toward carboxymethyl cellulose were determined. Both enzymes favored CMC and maintained 100% activity for 10 days at 38 °C. KCl, MgCl(2), HgCl(2), and FeCl(3) showed approximately 30% inhibition against EG Th1 but not ExG Th1. They catalyzed transglycosylation of glucose in the presence of cellobiose, but ExG Th1 exhibited better activity and higher product diversity.
Liu
Shu-Ying
SY
Department of Molecular Biotechnology, Da-Yeh University, Changhua 51591, Taiwan.
Shibu
Marthandam Asokan
MA
Jhan
Hua-Jing
HJ
Lo
Chaur-Tsuen
CT
Peng
Kou-Cheng
KC
D002475:Cellobiose / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013379:Substrate Specificity; D014242:Trichoderma / Q000201:enzymology*
D002475:Cellobiose; D006026:Glycoside Hydrolases; D005947:Glucose