Biology Reference
In-Depth Information
phosphorylase catalyzes phosphorolysis of sucrose in the presence
of inorganic phosphate (Pi) to produce Glc-1-P and fructose [2,3]. The
Glc-1-P thus produced can be used for the phosphorylase-catalyzed
synthesis of amylose. When these two enzymatic reactions were
individually conducted, the first reaction should be carried out in
high concentration of Pi, whereas the Pi should be removed as soon
as possible from the media of the second reaction. The combined
use of sucrose phosphorylase and phosphorylase in the production
of amylose from sucrose was reported by Waldmann et al. (Fig.
9.1) [4]. In this system, interestingly, Pi produced in the second
phosphorylase-catalyzed reaction is recycled for the first sucrose
phosphorylase-catalyzed reaction. Therefore, the cooperative action
by the two phosphorylases proceeds continuously with a constant
Pi concentration without any inhibition caused by an accumulation
of Pi.
The thermostable sucrose phosphorylase was created by
introducing a random and site-directed mutagenesis on the sucrose
phosphorylase gene from
to increase and
used together with the triple-mutant phosphorylase (F39L/N135S/
T706I) originally from potato for the production of amylose from
sucrose [5]. These thermostable variants of sucrose phosphorylase
and phosphorylase were employed to optimize the conditions for
the production of amylose from sucrose [6,7]. The yields of amylose
produced using the two enzymatic catalysis methods from sucrose
Streptococcus mutans
sucrose
sucrose
phosphorylase
Glc-1-P
amylose
phosphorylase
cellobiose
phosphorylase
cellobiose
Figure 9.1
Production of amylose by combined use of sucrose or cellobiose
phosphorylase and phosphorylase.
