Elimination of glucose contamination from adipocyte glycogen extracts

Abstract

Glycogen was quantified in rat adipocytes by isolation using conventional KOH digestion and ethanol precipitation, followed by hydrolysis and spectrophotometric assay of the glucose product. A concentration of 0.193 ± 0.020 [mu]mol glucosyl units/106 cells was recorded. When this procedure was modified by including a 4 h incubation with glucose oxidase prior to glycogen hydrolysis, the glycogen concentration was found to be 0.055 ± 0.008 [mu]mol glucosyl units/106 cells. Therefore in adipocytes, conventional glycogen assays give substantial overestimates due to incomplete removal of glucose during glycogen isolation. Contaminant glucose can be scavenged in a simple manner by incubation with glucose oxidase prior to glycogen hydrolysis.