|Title: ||Thermal inactivation of alkali stable xylanases (XylA & XylB) from alkali tolerant fungus Aspergillus fischeri Fxn 1: effect of trehalose on their thermostability|
|Issue Date: ||19-Jul-2005 |
|Additional Links: ||http://www.bioscience2005.org/|
|Abstract: ||Alkali tolerant fungus Aspergillus fischeri Fxn 1 secretes two xylanases,
an exoxylanase (XylA) and an endoxylanase (XylB) in solid state fermentation.
Kinetic studies showed that thermal inactivation of purified XylA
and XylB at pH 9, in the temperature ranging from 303K to 333K,
followed first-order kinetics, with denaturation rate constants as
9.6 10-3 and 8.2 10-3 at 323K for XylA & XylB respectively. Heat-inactivation
plots for purified enzymes were linear from which
thermodynamic activation parameters, ΔH#, ΔS# and ΔG# have been
estimated. The enzymatic activity was relatively stable with a respective
half-life (t1/2) at 323K of 72 min for XylA and 84.5 min for XylB. The half
life values of XylA & XylB increased to 169 and 136 min respectively, in
the presence of 1 M trehalose. Separate tests at 60
C in the presence of
additives (polyols, carbohydrates) showed that trehalose was the most
effective stabiliser, which increased the stability of XylA & XylB to 64.7 &
17.63 % respectively.|
|Description: ||Presented at Bioscience 2005 (Biochemical Society meeting), Glasgow, July 17-21, 2005.|
|Appears in Collections: ||Department of Biological Sciences Research: Fermentation and Industrial Microbiology (Biotechnology)|
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