|
|
|
Contents | Index |
8.1.1 Glucose activation
Glucose activation consists in the formation of UDP-glucose from glucose-6-phosphate, which to this end is converted to glucose-1-phosphate by the enzyme phosphoglucomutase. Glucose-1-phosphate is then activated to UDP-glucose by glucose-1-phosphate uridylyltransferase; this reaction uses uridine triphosphate (UTP) and releases pyrophosphate.1
1: Whereever pyrophosphate is released, it is subsequently cleaved to two phosphate ions by pyrophosphatase. This cleavage is exergonic and keeps the concentration of pyrophosphate low, which in turn makes the first reaction more exergonic. Release of pyrophosphate therefore provides a stronger driving force to a reaction than release of monophosphate.