Biology Reference
In-Depth Information
incubation at 80
°
C for 30 min [7]. Incubation of the
T. aquaticus
phosphorylase with various Glc-1-P/primer ratios at 70
C resulted
in synthesis of amylose with a distinct molecular weight. The
°
M
/
M
w
n
value of each amylose was almost 1, indicating the product had very
narrow molecular weight distribution. This narrow distribution
might reflect the fact that amylose does not form a precipitate at this
high reaction temperature. In this case, however, the maximum
M
w
5
of the product was 1.24
and the yield of amylose decreased as
the Glc-1-P/primer ratio increased.
It has been reported that the smallest primer for the glucan
synthesis reaction of potato phosphorylase is maltotetraose, and
the smallest substrate for the phosphorolysis was maltopentaose.
However, phosphorylase from
×
10
shows distinct substrate
specificity, where maltotriose is the smallest primer for glucan
synthesis and the maltotetraose is the smallest substrate for
phosphorolysis [7]. This unique substrate specificity is also an
advantage for the production of amylose because a cheaper primer
can be used.
T. aquaticus
4.3
Practical Applications of Phosphorylase-
Catalyzed Polymerization
Apparent production of an enzymatically synthesized amylose in
DMSO was carried out by means of the calcium alginate hydrogel
beads/DMSO system as the reaction field of the phosphorylase-
catalyzed polymerization (Fig. 4.2) [8]. When the calcium alginate
hydrogel beads including Glc-1-P, maltoheptaose, and phosphorylase
were suspended in DMSO and the system was slowly stirred at 40
C
for 12 h, the reaction proceeded to produce amylose, which eluted
to the DMSO solution. The time-curse experiment in the system
revealed that the enzymatic polymerization took place for 15 min on
the inside of the calcium alginate beads and the produced amylose
gradually eluted to the surrounding DMSO solution.
One of the significant characteristics in the phosphorylase-cata-
lyzed polymerization is to initiate the reaction from a nonreducing
end of the primer [9]. Therefore, the modified primers can be used
for the phosphorylase-catalyzed polymerization to introduce the
functional groups at the chain end of amylose or maltooligosaccha-
°
