Starch biosynthesis phosphorylase

Since D-fructose and D-glucose phosphates are amongst the first products of photosynthesis, and since starch (in plants) and glycogen (in animals) are converted by phosphorylase to D-glucosyl phosphate, biosynthesis of carbohydrates revolves around these ubiquitous compounds... 

In nature a cascade of enzyme-catalyzed reactions is involved for the biosynthesis of starch. When selecting the appropriate enzymes and reaction circumstances reactions with multiple enzymes can be performed in vitro. Synthetic glycogen was first synthesized in vitro by Cori [146] in 1943 via the cooperative action of muscle phosphorylase and branching enzymes isolated from rat liver and rabbit heart. 

This conclusion was confirmed by kinetic measurements. Preparations of purified cytosolic and plastidic phosphorylase isozymes from Pisum sativum were adjusted to an approximately equal activity concentration (as determined at saturating levels of soluble starch). Using these isozyme preparations kinetic measurements were performed at varying levels of the polysaccharide fraction. Orthophosphate or glucose 1-phosphate levels were saturating. The initial rates of phosphorolysis (Fig. 2A) or of polysaccharide biosynthesis (Fig. 2B) were determined. 

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