Adenosine-5′-diphosphoglucose

Adenosine-5′-diphosphoglucose (ADP-glucose) is found in acid and alcoholic extracts of plants and bacteria. There is no specific method for the determination of ADP-glucose. ADP-glucose can be converted to ATP and G-1-P with the help of inorganic pyrophosphate (PPi) and ADP-glucose pyrophosphorylase. This specific reaction is the basis for the method for the determination of ADP-glucose. The method has application in biochemistry. The principle behind the method is that the increase of NADPH, as measured by the change in extinction at 340 (334, 365) nm, is proportional to the amount of ADP-glucose present. The pH optima of the enzymes catalyzing reactions are between 7.5 and 8.5; therefore, the measurements should be made in this range. Spectrophotometer or spectrum-line photometer is suitable for accurate measurements at 340 nm, 334 nm, or 365 nm. The chapter discusses the purity of reagents. The enzymes should be free from PPi. The enzymes must not contain any NADPH oxidase.