Glycogen periodate oxidation

More than 80 different samples of glycogen have now been assayed by periodate oxidation,and of these, 70 had C. L. values of 10-14. ... 

In similar studies, glycogens (of cat liver. Helix pomatia, Mytilus edulis, and Tetrahymena pyriformis) after prolonged periodate oxidation, were hydrolyzed with acid. The hydrolyzate of Helix glycogen yielded a trace of D-glucose, equivalent to <1 % of (1 2) or (1 —> 3) linkages the other... 

The acid hydrolyzate of a periodate-oxidized glycogen of unspecified origin, and of the derived polyalcohol, contained 1 % of D-glucose. Although it was suggested that this arose from (1 —> 2) or (1 —> 3) linkages, the... 

Periodate-oxidation studies have thus shown that, in several glycogens, over 99 % of the inter-chain linkages are (1- 6), and experiments emplo5nng partial hydrolysis hy acid indicate that these linkages have an a-n-con-figuration. 

Methods of measurement (1) = light-scattering (s) = sedimentation-diffusion (o) = osmotic pressure of the methylated glycogen. Methods of assay (m) = meth-ylation (p) = periodate oxidation. This sample was polydisperse a minor component had a molecular weight of 0.5 X 10 . 

Methods of assay (m) = methylation (p) = periodate oxidation (e) = enzymic. B.V. = Blue Value (compare Refs. 3 and 4). Xmax = wavelength of maximum absorption of polysaccharide-iodine complex. Priming activity toward P-enzyme soluble starch = 1.0. Priming activity toward muscle phosphorylase glycogen = 100, corn amylopectin = 63. Molecular weight, 64,000 (compared with about 100,000 for the parent amylose). 

Table VII shows, for a number of glycogens and amylopectins, a comparison of the results of c.l. determinations by enzymic methods with those obtained by periodate oxidation these show the high degree of agreement among the results obtained by die various methods.

Glycogen differs only slightly from amylopectin, and studies such as methylation, hydrolysis, and periodate oxidation yield closely similar results for the two polysaccharides. These do establish, however, that there are... 

During the recovery period from exercise, ATP (newly produced by way of oxidative phosphorylation) is needed to replace the creatine phosphate reserves — a process that may be completed within a few minutes. Next, the lactic acid produced during glycolysis must be metabolized. In the muscle, lactic acid is converted into pyruvic acid, some of which is then used as a substrate in the oxidative phosphorylation pathway to produce ATP. The remainder of the pyruvic acid is converted into glucose in the liver that is then stored in the form of glycogen in the liver and skeletal muscles. These later metabolic processes require several hours for completion. 

After a period of intense muscular activity, the individual continues breathing heavily for some time, using much of the extra 02 for oxidative phosphorylation in the liver. The ATP produced is used for gluconeogenesis from lactate that has been carried in the blood from the muscles. The glucose thus formed returns to the muscles to replenish their glycogen, completing the Cori cycle (Fig. 23-18 see also Box 15-1). 

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