Biology Reference
In-Depth Information
Chapter 9
Carbohydrate Engineering by
Phosphorylase Catalysis
9.1
Facile Synthesis of Glc-1-P from Starch by
Thermus Caldophilus
GK24 Phosphorylase
As described in the previous chapters, phosphorylase is useful for
the practical production of amylose, but the problem is that Glc-1-P
is expensive.
GK24 phosphorylase was used to
synthesize Glc-1-P from an inexpensive starch [1]. The optimal pH
and temperature were 7.0 and 70
Thermus caldophilus
C in the phosphorylase reaction
with starch producing Glc-1-P. Soluble starch (amylopectin, amylose)
turned out to be a better substrate giving a higher yield of Glc-1-P
than
°
4)-glucans (glycogen, potato starch,
etc.). As a result, Glc-1-P was obtained in a good yield (47%) from the
reaction containing 5% soluble starch in 0.7 M potassium phosphate
at pH 7.0. Therefore, it can be considered that
α
-(1
6)-branched
α
-(1
T. caldophilus
phosphorylase is readily utilized in large-scale synthesis of Glc-1-P.
9.2
Amylose Production by Combined Use of
Phosphorylase with Other Phosphorylases
One possible solution to the expensive problem of Glc-1-P is
to
combine
another
enzyme
that
produces
Glc-1-P.
Sucrose
