Spectrophotometric Methods for the Study of Eukaryotic Glycogen Metabolism

Glycogen is synthesized as a storage form of glucose by a wide array of organisms, ranging from bacteria to animals. The molecule comprises linear chains of α1,4-linked glucose residues with branches introduced through the addition of α1,6-linkages. Understanding how the synthesis and degradation of glycogen are regulated and how glycogen attains its characteristic branched structure requires the study of the enzymes of glycogen storage. However, the methods most commonly used to study these enzyme activities typically employ reagents or techniques that are not available to all investigators. Here, we discuss a battery of procedures that are technically simple, cost-effective, and yet still capable of providing valuable insight into the control of glycogen storage. The techniques require access to a spectrophotometer, operating in the range of 330 to 800 nm, and are described assuming that the users will employ disposable, plastic cuvettes. However, the procedures are readily scalable and can be modified for use in a microplate reader, allowing highly parallel analysis.