Kinetics and thermodynamic of the purified dextranase from Chaetomium erraticum

• Published in: Journal of molecular catalysis. B, Enzymatic Vol. 122; pp. 80 - 86
• Main Authors: Virgen-Ortíz, J.J., Ibarra-Junquera, V., Escalante-Minakata, P., Ornelas-Paz, J. de J., Osuna-Castro, J.A., González-Potes, A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2015
• Subjects: Chaetomium erraticum; Dextran; Dextranase; Isomalto-oligosaccharides; Kinetic properties; Dextran; Isomalto-oligosaccharides; Kinetic properties; Chaetomium erraticum; Dextranase
• ISSN: 1381-1177; 1873-3158
• DOI: 10.1016/j.molcatb.2015.08.020

[Display omitted] ⿢Detailed investigation into kinetic and thermodynamic parameters.⿢DN was characterized as a temperature-resistant biocatalyst.⿢IMOs, prebiotic, were the main end-products of dextran hydrolysis.⿢Ca2+ and Co2+ were found to enhance dextranase activity. Dextranase (DN) has generated interest due to its ability to hydrolyze dextran for the synthesis of isomalto-oligosaccharides (prebiotic). Here, DN from Chaetomium erraticum was purified by a combination of tangential ultrafiltration and ion-exchange chromatography, and then the enzyme was characterized. This enzyme has a molecular weight (Mw) of around 59kDa, calculated by SDS-PAGE, and an Mw of 120kDa estimated on zymogram, suggesting that the native form is a dimer. The purified DN exhibited a pH and temperature optimum of 5.2 and 60°C, respectively. The DN-catalyzed hydrolysis of dextran followed Michaelis⿿Menten kinetics with Km and Vmax values estimated as 2.6±0.1% (260μM) and 2280±9μmolmin⿿1mg⿿1 protein, respectively. The activation energy was determined as 52.7±0.4kJmol⿿1, and the thermodynamic parameters (οG⿡, οH⿡ and οS⿡) for the hydrolysis of dextran were also determined. Dextranase activity was enhanced by Ca2+, and especially Co2+ at 1mM, which improved its activity to 124.5±3.0%, whereas Ni2+ and Fe3+ negatively affected activity. The main end-products of 100kDa dextran hydrolysis by DN were isomaltose, isomaltotriose, and maltopentaose. Finally, it was found that the thermal inactivation mechanism for dextranase can be described by the first-order irreversible mechanism.