Extraction of glycogen on mild condition lacks AIG fraction

Z. Ghafouri, M. Rasouli

Department of Clinical Biochemistry and Immunogenetic Research Center, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Mazandaran, Iran. mehdi.rasouli@yahoo.com

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• Metabolism

OBJECTIVE: Extraction of animal tissues with cold water or perchloric acid yields less glycogen than is obtained with hot-alkaline. Extraction with acid and alkaline gives two fractions, acid soluble (ASG) and insoluble glycogen (AIG). The aim of this work is to examine the hypothesis that not all liver glycogen is extractable by Tris-buffer using current techniques.

MATERIALS AND METHODS: Rat liver was homogenized with Tris-buffer pH 8.3 and extracted for the glycogen fractions, ASG and AIG. The degree of homogenization was changed to remove all glycogen.

RESULTS: The content of glycogen was 47.7 ± 1.2 and 11.6 ± 0.8 mg/g wet liver in the supernatant and pellet of the first extraction respectively. About 24% of total glycogen is lost through the first pellet. Increasing the extent of homogenization from 30 to 180 sec and from 15000 to 20000 rpm followed with 30 sec ultrasonication did not improve the extraction. ASG and AIG constitute about 77% and 23% of the pellet glycogen respectively.

CONCLUSIONS: Extraction with cold Tris-buffer failed to extract glycogen completely.  Increasing the extent of homogenization followed with ultrasonication also did not improve the extraction. Thus it is necessary to re-examine the previous findings obtained by extraction with cold Tris-buffer.

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