The utilization of glycogen by skeletal muscle was, at one time, one of the central problems of biochemistry. Attention focused on the most dramatic property of the system: the very rapid glycogenolysis that occurs synchronously with muscle contraction. This phenomenon now has a generally accepted explanation : the increase in Ca2+ that induces muscle contraction also activates phosphorylase ki...

The enzymes of glycogen metabolism are regulated by interconversion between phosphorylated and dephosphorylated forms. In contrast with our well-defined knowledge of the phosphorylation processes of different enzymes and their role in glycogen breakdown and synthesis, the phosphatases catalysing the reverse processes are only now being understood. The regulation of dephosphorylation reactions i...

We employed our newly developed, continuous, spectrophotometric method [Sergienko and Srivastava (1994) Anal. Biochem. 221, 348-355] for measuring the glycogen-phosphorylase-catalysed reaction in the direction of glycogen synthesis, utilizing varied concentrations of AMP (2-400 microM) and glucose 1-phosphate (G1P; 4 microM to 41 mM). The experimental data revealed that the enzyme catalysis exh...

Entamoeba histolytica is a parasitic protozoan that causes diarrheal disease in approximately 100 million people worldwide every year. E. has two forms, the growing trophozoite and infectious cyst. Trophozoites colonizing large intestine form cysts are released into environment. The ingestion of contaminated food water continues cycle. Here, we investigated role glycogen growth encystation. Gly...

The mechanism of liver glycogen synthesis after refeeding has been investigated in diabetic rats, diabetic insulin-treated rats, and in control rats fasted for 48 h. The accumulation of liver glycogen was the same in diabetic rats and in control rats after 2 h of feeding, but did not proceed any further in the diabetic group during the next 2 h. Insulin-treated diabetic rats synthesized five ti...

Fructose has been shown to have a catalytic effect on glucokinase activity in vitro; however, its effects on hepatic glycogen metabolism in humans is unknown. To address this question, we used (13)C nuclear magnetic resonance (NMR) spectroscopy to noninvasively assess rates of hepatic glycogen synthesis and glycogenolysis under euglycemic (approximately 5 mmol/l) hyperinsulinemic conditions (ap...