|
A. S. Dotsenko, A. V. Gusakov, A. M. Rozhkova, P. V. Volkov, O. G. Korotkova, A. P. Sinitsyn
Enzymatic
hydrolysis of cellulose using mixes of mutant forms of cellulases from Penicillium
verruculosum
Abstract
Cellulases are
the major components of multienzyme systems that found applications in the
processes of bioconversion of renewable lignocellulosic feedstocks to various
useful products. A comparison of hydrolytic efficiency of enzyme mixes based on
recombinant wild-type endoglucanase II, cellobiohydrolases I and II from Penicillium
verruculosum fungus (in the presence of Aspergillus niger
β-glucosidase) with mixes of mutant forms of these enzymes in hydrolysis
of cellulosic materials was carried out, and the influence of temperature and
substrate concentration on the glucose yield was studied. The mutant cellulases
represented proteins, in which N-linked glycans have partially been removed
using site-directed mutagenesis. In hydrolysis of microcrystalline cellulose
and milled aspen wood by mixes of mutant cellulases, the yields of glucose
after 24–72 h of the enzymatic reaction were higher by 31–38% and 11–27%,
respectively, relative to the compositions based on the wild-type enzymes. On
variation of hydrolysis temperature in the range of 40–60 ºC, using mutant enzyme compositions, the highest product
concentrations were achieved at 50 ºC. Increasing
the substrate concentration in the reaction system from 5 to 50 g/l (while
maintaining the enzyme dosage at the same level) led to a 2,6–2,8-fold increase
in the glucose yield, accompanied by a decrease in the cellulose conversion
degree.
Key words: Penicillium
verruculosum, cellulase, endoglucanase, cellobiohydrolase, enzyme mutant
forms, N-glycosylation.
Copyright (C) Chemistry Dept., Moscow State University, 2002
|
|
