Variation in the degree of branching of the glycogens and an approximate relationship between average exterior chain length and iodine staining

Abstract

SynopsisPrecise evaluation of the branching characteristics of glycogen complex from a variety of sources was made by replicate determinations of end groups by a reproducible periodate oxidation method and by replicate determinations of the percentage degradation by exhaustive 0-amylase activity. Also, the iodine staining characteristics of these samples were studied. The following observations were made. During the synthesis of glycogen by baker's yeast. there was a significant increase in the average chain length of the glycogen, and the maximal optical absorbance AM of the glycogen-iodine complex doubled. The AM decreased linearly with increasing temperature, and increases in iodine concentration caused increases in both the AM and the wavelength of maximal absorbance. There was a general increase in the AM of the glycogen with increasing exterior chain length, hut there were minor deviations due to some dependence on the source of the glycogen. Unlike the linear relationship between the AM per chain and the average chain length of the amyloses, the A M per chain was exponentially related to the average exterior chain length of the glycogens.

Characterization of intracellular polysaccharides of Streptomyces

“…The average chain length of the polysaccharides was determined by oxidation with sodium metapenodate (Fales 1959) using a-methyl D-glucoside as a standard.…”

“…The iodine complexes were prepared by adding 2.5 mL of polysaccharide solution (2 mg of polysaccharide in 10 mL of water) to 2.5 mL of iodine reagent. The iodine reagent was prepared as described by Fales (1980). The absorption spectra were recorded between 400 and 700 nm against an iodine-iodide reference solution without polysaccharide.…”