No abstract

No abstract

SynopsisA procedure has been developed for characterizing cellulose ethers on the basis of the distribution of substituent groups along the polymer backbone. This method has been applied to carboxymethylcellulose. The technique uses cellulase, a cellulose-degrading enzyme. Degradation as a function of time is followed by viscosity and reducing sugar measurements. The combination of these data, along with other analytical results, provides information on the number of unsubstituted anhydroglucose residues and the number and average length of blocks of two or more contiguous unsubstituted residues. The results obtained on a series of carboxymethylcellulose samples indicate that the rate of degradation and the number and length of blocks of unsubstituted residues depends not only on the number of substituent groups, but also on other molecular parameters.

No abstract

SynopsisCircular dichroism spectroscopy has been used to study t.he interactions of hyaluronic acid, heparitin sulfate, and keratan sulfate with cationic polypeptides. The results indicate that the presence of these mucopolysaccharides has an effect in the conformation of poly(L-lysine) and poly(L-arginine), such that the former adopts the "random" form and the latter takes up the or-helical conformation, rather than the "charged coil" form expected a t neutral pH. The relative strengths of the interactions can be judged from the melting temperatures above which they are disrupted. Both the stoichiometry and the strength of the interactions depend on the position, number, and type of anionic groups attached to the polysaccharide backbone. Such considerations place the six common mucopolysaccharides in order of increasing strength of interaction: hyaluronic acid < chondroitin 4-sulfate < heparitin sulfate < chondroitin 6-sulfate < keratan sulfate 6 dermatan sulfate. These differences should be paralleled by differences in the interaction of the mucopolysaccharides with collagen and fibrous proteins.