Untersuchungen zur biosynthese der cellulose in der alge valonia

Molecular weight distribution of cellulose in primary cell walls : Investigations with regenerating protoplasts, suspension cultured cells and mesophyll of tobacco

The distribution pattern of the degree of polymerization (DP) of cellulose present in the cell walls of mesophyll- and suspension-cultured cells of tobacco was compared to that of newly synthesized (14)C-labeled cellulose from regenerating tobacco protoplasts and suspension-cultured cells. The cellulose was nitrated, and, after fractionation according to differences in solubility in acetone/water, the DP pattern of labeled or unlabeled cellulose nitrate was determined by viscosity measurements. A low (DP<500) and high DP-fraction (DP>2500) of cellulose were predominant in the cell walls of protoplasts, suspension - cultured cells, and mesophyll cells. The average DP of the high molecular weight fraction of cellulose in the cell walls of mesophyll was higher (DP∼4,000) than in protoplasts or suspension - cultured cells (DP 2,500-3,000). In all cell walls tested, minor amounts of cellulose molecules with a broad spectrum of a medium DP were present. Pulse - chase experiments with either protoplasts or suspension -cultured cells showed that a large proportion of the low and medium DP-cellulose are a separate class of structural components of the cellulose network. The results are discussed in relation to the organization of cellulose in the primary cell wall.

Further characterization of the alkali-stable material from the scales of Pleurochrysis scherffelii: A cellulosic glycoprotein

Crude and alkali-purified fractions of scales isolated from the haptophycean alga Pleurochrysis scherffelii Pringsheim were analyzed. The predominantly cellulosic nature of the fibrillar, alkali-resistent polysaccharide component has been confirmed by gas chromatography of the hydrolysate, by X-ray diffraction and by viscosimetric studies using the nitrified product. Peptide material is covalently linked to this cellulosic structural polysaccharide and remains associated with it through the harsh purification treatments. The amino acid composition of this peptide moiety is given. The relationship of this cellulosic "glycoprotein" to other cell wall glycoproteins is discussed and possible functions during the formation and secretion of wall materials are hypothesized.