title: Stability and activity of Dictyoglomus thermophilum GH11 xylanase and its disulphide mutant at high pressure and temperature.
abstract: The functional properties of extremophilic Dictyoglomus thermophilum xylanase (XYNB) and the N-terminal disulphide-bridge mutant (XYNB-DS) were studied at high pressure and temperature. The enzymes were quite stable even at the pressure of 500MPa at 80°C. The half-life of inactivation in these conditions was over 30h. The inactivation at 80°C in atmospheric pressure was only 3-times slower. The increase of pressure up to 500MPa at 80°C decreased only slightly the enzyme's stability, whereas in 500MPa the increase of temperature from 22 to 80°C decreased significantly more the enzyme's stability. While the high temperature (80-100°C) decreased the enzyme reaction with short xylooligosaccharides (xylotetraose and xylotriose), the high pressure (100-300MPa) had an opposite effect. The temperature of 100°C strongly increased the Km but did not affect the kcat to the same extent, thus indicating that the interaction of the substrate with the active site suffers before the catalytic reaction begins to decrease as the temperature rises. Circular dichroism spectroscopy showed the high structural stability of XYNB and XYNB-DS at 93°C.
authors: Department of Biotechnology and Chemical Technology, School of Chemical Technology, Aalto University, P.O. Box 16100, 00076 Aalto, Finland. Electronic address: lihe1985@hotmail.com.
authors: He
authors: H
authors: Li
authors: Department of Biotechnology and Chemical Technology, School of Chemical Technology, Aalto University, P.O. Box 16100, 00076 Aalto, Finland.
authors: Sanni
authors: S
authors: Voutilainen
authors: Department of Biotechnology and Chemical Technology, School of Chemical Technology, Aalto University, P.O. Box 16100, 00076 Aalto, Finland.
authors: Heikki
authors: H
authors: Ojamo
authors: Department of Biotechnology and Chemical Technology, School of Chemical Technology, Aalto University, P.O. Box 16100, 00076 Aalto, Finland.
authors: Ossi
authors: O
authors: Turunen
mesh_terms: D001419:Bacteria / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001709:Biotechnology; D002942:Circular Dichroism; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D006358:Hot Temperature; D006868:Hydrolysis; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D011312:Pressure; D017433:Protein Structure, Secondary; D014990:Xylans / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D014990:Xylans; D043364:Endo-1,4-beta Xylanases
keywords: Dictyoglomus thermophilum; GH11 xylanase; Hydrolysis pattern; Pressure stability; Thermostability