Biology Reference
In-Depth Information
Chapter 2
General Scope for Enzymatic Tools in
Engineering of Polysaccharide Materials
2.1
Characteristic Features of Enzymatic
Reactions for Synthesis of Polysaccharides
All the biosubstances, including polysaccharides, are produced
in vivo
by enzymatic catalysis. Because enzymatic catalysis has attracted
much attention and grown in importance in biochemistry, organic
chemistry, and polymer chemistry, fundamental research studies
on enzymes and enzymatic reactions are still one of the main topics
in these research fields. Enzymes are generally categorized into six
main classes, which are oxidoreductases (EC 1), transferases (EC 2),
hydrolases (EC 3), lyases (EC 4), isomerases (EC 5), and ligases (EC 6)
[1]. In the main classes, two enzymes, i.e., transferases and hydrolases,
have been practically applied as catalysts for the
enzymatic
synthesis of polysaccharides [2,3]. In general, enzymatic catalysis has
the following advantageous characteristics: (1) progress of reactions
under mild conditions, (2) high selectivities of stereo-, regio-,
enantio-, and chemoregulations leading to structurally controlled
products, and (3) large turnover numbers. These characteristics
of enzymatic catalyses induce the following expectations for the
precision synthesis of polysaccharides: (1) perfect control of stereo-
and regioselectivities in glycosidic linkages, (2) production of new
in vitro
