The Chemistry of Protopectin: A Critical Review of Historical Data and Recent Developments
1963; Academic Press; Linguagem: Inglês
10.1016/s0065-2628(08)60064-6
ISSN1875-6352
Autores Tópico(s)Polysaccharides Composition and Applications
ResumoPublisher Summary Present knowledge of pectic substances in plant tissues is based mainly on histological and histochemical studies. This chapter reviews the extensive literature on the chemistry of protopectin. On the basis of the evidence available at present, it is not possible to determine unequivocally which of the several possible but still hypothetical combinations is likely to account for the solubility characteristics of native pectins. It is possible that pectin substances in different plants and in different parts of the same plant are chemically bound or physically anchored in different ways. Additional evidence is needed from carefully obtained tissue preparations from material properly identified physiologically and histologically. It appears, based on present evidence, that the most likely explanation of the relative insolubility of protopectin is that it exists as a polygalacturonide in which the hydroxyl groups on carbon atoms C4 and C5 are masked by glycosidic and ring formation, and the carboxyl group on C1 is either free, esterified with methyl alcohol, or esterified with araban, galactan, or some other polysaccharide. The hydroxyl on carbon atoms C2 and C3 may be free, esterified with acetyl groups, or linked by ether-like linkage to polysaccharides or lignins. The degree of acetylation is a factor in determining the extractability of pectin and its combination with other cell-wall constituents.
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