Clarence A. Knutson

A new modification of the carbazole analysis: Application to heteropolysaccharides

Abstract The carbazole analysis when run at 55° in the presence of borate gives increased sensitivity for d -galacturonic, d -mannuronic, and l -guluronic acids, while greatly decreasing that of d -glueuronic acid. Comparison of values from these reaction conditions with values from other modifications of the carbazole analysis reveals a high degree of specificity of the reaction for each acid under any defined set of conditions. This specificity is of value for identification of unknown uronic acids. The new modification is especially useful for determination of d -mannuronic acid in heteropolysaccharides.

Determination of the composition of uronic acid mixtures.

Abstract A method has been developed to determine the relative proportions of three uronic acids in a compound or mixture, which uses data obtained from analysis of samples by the carbazole method under four different reaction conditions. The method works equally well with synthetic mixtures and natural products, such as alginates.

Properties of amylose-iodine complexes prepared in the presence of excess iodine

Abstract A potentiometric-titration procedure, in which samples are always exposed to an excess of I2-KI has been developed for measuring iodine-binding capacity of starches. Binding capacity of amylose under these conditions is ∼30% as opposed to 20% by conventional potentiometric titration. Spectrophotometric absorbance is essentially the same for either method, but is proportional to potentiometric values only in the excess-iodine titration procedure. Effects of variation of concentration of I2, KI, and phosphate buffer and of temperature on the reaction have been examined. Calculations based on concentration of reactants in solution indicate that the binding species varies from I3− at 10−1 m KI to I11− at 5 × 10−4 m KI.

Composition and properties of the extracellular polysaccharide produced by arthrobacter stabilis NRRL B-3225

Abstract The extracellular polysaccharide produced by Arthrobacter stabilis NRRL B-3225 contains d -glucose, d -galactose, pyruvic acid, O-succinyl, and O-acetyl in the approximate molar ratio of 6:3:1:1:1.5. Succinyl is linked as its half-ester, making it a readily removable, acidic function that imparts versatility to the polysaccharide both for fundamental research and for commercial use. The viscosity of aqueous, salt-free solutions of both native and deacylated polymer is relatively low, but atypical of anionic polysaccharides, increases rapidly in the presence of salts, acids, or alkali.

Paper-chromatographic separation of [3H]borohydride-reduced hexoses for quantitative determination of polysaccharide composition

Abstract An improved procedure for determination of composition of heteropolysaccharides by radiochromatography of sodium [3H]borohydride-reduced hydrolyzates has been developed. The method is accurate and sensitive, is less cumber-some and more reliable than similar procedures currently in use, and permits, for the first time, compositional analysis of hydrolyzates containing both hexoses and uronic acids in a single radiochromatographic procedure.