| LITERATURE REF. |
Authors at Co. also is using enzymes to modify and improve the properties of polysaccharides such as pectins. Pectins occur in cell walls of plants and cement the cells together. They are soluble in water but insoluble in alcohol and other organic solvents. The compounds consist mainly of galacturonic acid sequences interrupted by rhamnopyranose residues. Many of the galacturonic acid residues are methoxylated. " Pectin is commercially available and is used extensively as gelling agents, thickeners, stabilizers, and emulsifiers," author notes. "The degree and sequence distribution of methoxylation, the distribution of rhamnopyranoses, and the molecular weight influence its gelation properties. For pectin with a high methoxy content, gelation can occur through the addition of an aqueous solution of sucrose and citric acid." In 2000, the Co. s team patented an enzymatic process for modifying high-methoxy pectin with l-amino acids to produce pectins with improved gelling properties. Although pectic enzymes are known in nature, the enzymes used for the Co. s process are nonpectic, according to author. "We used papain obtained from papaya to work on pectin, which is not a natural substrate of the enzyme," he tells C&EN. "Papain is a protease and is normally used to hydrolyze proteins--for example, to tenderize meat. Papain was not previously known to react with pectin. We brought an unnatural pair together and used them in synthesis--for the coupling reaction between pectin and amino acids." The researchers determined the strength, in terms of rheological properties, of pectins modified by a variety of amino acids. The strongest gel was formed by high-methoxy pectin modified with L-arginine. The group suggests that the amino acid-modified pectin derivatives may potentially be useful in industry as gelling or thickening agents and also in cosmetic formulations and drug delivery systems |
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