Biomedical Engineering Reference
In-Depth Information
generating reducing sugar. Gao separated protein in
Trichoderma pseudokoningii
filtrate with a molecular weight of about 24
10
4
, pI 7.0. It could make cotton fiber
and chitin expand without producing reducing sugar. The infrared spectrum showed
that it indeed could weaken the absorption intensity of the cotton fiber hydrogen
bonding zone. It is now generally believed that natural cellulose opens the hydrogen
bond among the cellulose chain and intrachain at first with a nonhydrolyzable factor
and hydrogen bond enzyme. Then, disordered noncrystalline cellulose is formed
and consequently hydrolyzed into fiber dextrin and glucose under the synergy effect
of three kinds of enzymes.
11.2.5.5
Research on Nonenzyme Catalysis and Oxidation
of Cellulose [
54
]
In
T. pseudokoningii
and
Gloeophyllum trabeum
culture filtrate, pure capillary
electrophoresis peptide components are separated, including single-fiber generation
factor (SFCF) and
Gloeophyllum trabeum
(Gt). With the development of electron
spin resonance (ESR), the capture of hydroxyl radicals (HO
•
) and superoxide
anion radicals (O
2
•
) becomes possible. They lead to changes in physical and
chemical properties of cellulose, and the following mechanism was proposed: The
short-peptide compound complex reduces iron (Fe
3C
), activates molecular oxygen,
triggers a Fenton reaction and oxidizes cellulose hydroxyl, promotes glycosidic
strand breaks, and forms short fiber. It was proved that oxidative degradation is
an integral part of cellulose biodegradability.
11.2.5.6
Research on Characterization of the Topological Structure
of the Cellulase Molecule [
54
]
After limited digestion by papain and a series of separation and purification, the
catalytic domain and CBD are obtained from
Trichoderma
endo- and exocellulase.
Whole-enzyme molecules of CBH I and EG I are measured. The adsorption and
desorption capacity of the two domains on the fiber material and the specific
activity of hydrolyzing several fiber materials are also detected. Results showed
that although a single catalytic domain or CBD still has hydrolysis and adsorption
capacity, when any single structural domain or two domains, is mixed with the same
amount of substance, the hydrolysis or the adsorption capacity is much less than its
corresponding enzyme molecules. For example, the CBD and catalytic domain of
CBH I can adsorb on cotton fiber, but it is easily eluted. While the whole enzyme
molecule adsorbed, it could not be eluted down even with 1 M NaCl. The synergetic
effect of CBH I and EG I on the degradation of crystalline cellulose can only be
reflected when the two enzyme molecules react together. The synergistic capacity
can be significantly reduced while using four domains mixed with an equal amount.
