Glycogen extraction from tissues

Glycogens may be extracted from tissue with hot water, dilute trichloroacetic acid, or chloral hydrate but are usually removed by hot 30% potassium hydroxide solution. They are usually precipitated from the latter solution by alcohol. Some possibility exists that the alkaline extraction causes degradation 18, 19). 

Glycogen may be isolated from tissues by extraction with concentrated alkali at 100 , with chloral hydrate at 80°, or with cold aqueous trichloroacetic acid. 

The MAS does not represent a rapid throughput procedure, but because there is no sample extraction or other manipulation prior to analysis, it represents an unbiased method in which changes in tissues can be studied, and as appropriate, compared to alterations observed in biofluids. In this manner, MAS is synergistic with and complimentary to analysis of biofluids by metabonomic applications. Figure 2 shows the typical NMR-MAS spectra from the liver of a control and galactosamine-treated rat. This method readily detects glucose and glycogen, choline and related metabolites and a variety of lipids, and fatty acids. An example of the utility of NMR-MAS data in concert with biofluid analyses is described later in this review. 

The proposed structure did not, however, explain the observed lack of reducing power of glycogen Haworth and Percival suggested that, during extraction of glycogen from animal tissues with concentrated alkali, modification of the reducing group occurs. 

Glycogen is relatively stable in hot 30 per cent. KOH or NaOH, and may be extracted by these reagents from fresh, finely minced tissues. It is purified by alcoholic reprecipitations, and by dialysis. 

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