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Facile synthesis of glucose-1-phosphate from starch by Thermus caldophilus GK24 α-glucan phosphorylase

Paper ID Volume ID Publish Year Pages File Format Full-Text
36578 45137 2005 7 PDF Available
Title
Facile synthesis of glucose-1-phosphate from starch by Thermus caldophilus GK24 α-glucan phosphorylase
Abstract

The glgP gene encoding α-glucan phosphorylase (α-GP) from the thermopile Thermus caldophilus GK24 has been identified, cloned, and overexpressed in Escherichia coli and used to synthesize d-glucose-1-phospate (G1P) from an inexpensive starch. The enzyme, purified 6.5-fold, was isolated in 31% yield from the transformed E. coli, and gave a single band. The purified enzyme may exist as a homohexamer with an apparent molecular mass of a 550 kDa molecule, consisting of 90 kDa per subunit. The optimal pH and temperature were 7.0 and 70 °C in the α-GP reaction with starch producing G1P. Soluble starch (amylopectin, amylose) turned out to be a better substrate giving a higher yield of G1P than α-1,6-branched α-1,4-glucans (glycogen, potato starch, etc.). As a result, G1P was obtained in a good yield (47%, w/w) from the reaction containing 5% (w/v) soluble starch in 0.7 M potassium phosphate at pH 7.0. T. caldophilus α-GP shows a high tolerance (up to 0.7 M) of potassium phosphate and plays a critical role in shifting the reaction equilibrium in favor of G1P synthesis. The G1P product can be purified simply by ethanol precipitation, after removing the unreacted starch and inorganic phosphate by activated charcoal and magnesium acetate precipitation. It is concluded that T. caldophilus α-GP readily utilized in large scale synthesis of G1P.

Keywords
Enzymatic synthesis; α-Glucan phosphorylase; Glucose-1-phosphate; Glycogen; Starch; Thermus caldophilus
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Facile synthesis of glucose-1-phosphate from starch by Thermus caldophilus GK24 α-glucan phosphorylase
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 40, Issue 12, December 2005, Pages 3707–3713
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us