AN ANALYSIS OF AVENA COLEOPTILE PECTIN FRACTIONS

Abstract

Extraction and determination of pectic materials from growing plant tissues is often complicated by overlapping solubilities and lack of specificity of the pectin assay utilized. We find that the hot water soluble, hot versene soluble, and residual uronide components of Avena coleoptile cell wall represent at least three distinct pectin fractions with little or no overlap in solubility. In situations where hexose interference in colorimetric pectin determinations became appreciable, the polyanhydrogalacturonic acid content of the extract was determined by measurement of isolated galacturonic acid released through the specific action of polygalacturonase.A fourth fraction containing pectin-like materials was extracted from whole tissue in cold acetate buffer. This fraction was associated with heat-stable protein. No pectin identified as polyanhydrogalacturonic acid was found in the cytoplasmic fraction by the same techniques used for identifying pectin on cell wall derived fractions.