B. Nidetzky et al., ENZYMATIC-SYNTHESIS OF ALPHA-GLUCOSE-1-PHOSPHATE - A STUDY EMPLOYING A NEW ALPHA-1,4 GLUCAN PHOSPHORYLASE FROM CORYNEBACTERIUM-CALLUNAE, Journal of carbohydrate chemistry, 14(7), 1995, pp. 1017-1028
In synthetic pathways to complex carbohydrates such as oligosaccharide
s or nucleotide sugars the activated sugar l-phosphates serve as impor
tant starting molecules. In this study the enzymatic synthesis of alph
a-glucose-l-phosphate (Glc-1-P) has been investigated using a new bact
erial alpha-glucan phosphorylase from Corynebacterium callunae. The ma
jor factors governing the rate of reaction and the attainable degree o
f substrate conversion have been identified and, accordingly, for opti
mizing the yield and limiting reaction time for the enzymatic process
several points must be considered: (i) the pH-dependent equilibrium of
reaction, (ii) product inhibition of the phosphorylase and (iii) enzy
matic cleavage of alpha-1,6 glycosidic linkages present in alpha-1,4-g
lucans such as starch or maltodextrins by pullulanases to improve thei
r phosphorolytic conversion. Results obtained in continuous experiment
s with the phosphorylase retained in an ultrafiltration membrane react
or confirmed the complete operational stability of the enzyme for seve
ral days at 30 degrees C. Since no more than approximately 18% of the
inorganic phosphate can be converted into Glc-I-P an efficient procedu
re for phosphate and product recovery will be particularly important.