The enzymic degradation of pectin and other polysaccharides. I.—Introduction, and a preliminary study, on the degradation of the polysaccharides of fruits by the enzymes produced by micro‐fungi (‘moulds’)

Abstract

The polysaccharidases occurring in enzyme preparations from micro‐fungi, and used in the commercial processing of fruit products, have been examined. It has been shown that the majority of the preparations and cultures of micro‐fungi examined produced enzymes capable of degrading polygalacturonic acid, araban, galactan, xylan, etc. The occurrence in fruits of a mixture of polysaccharides and the presence of the appropriate hydrolases in the enzyme preparations raises certain difficulties in the standardization of these preparations for technological use. In addition, the estimation of the glycosidic hydrolysis of pectin produced by such preparations will consist of the total hydrolysis of polygalacturonic acid, araban and galactan; the assay of polygalacturonase activity by estimation of glycosidic hydrolysis may consequently be inaccurate. The simultaneous degradation of these three polysaccharides in relation to glycosidic hydrolysis, the secondary change in colloidal properties and the structure of pectin, is discussed. Evidence is presented suggesting that the enzymic hydrolysis of pectic acid occurs in two stages, which may be due to separate enzyme actions : the hydrolysis of araban and galactan, and the hydrolysis of polygalacturonic acid. The use of enzymes as analytical tools in the examination of pectin is indicated, and emphasis is laid on the desirability of preparations having a single enzyme activity.

Nutritional Studies With Lactobacillus Fermenti

“…The solvent mixture (n-butanol:ethanol:water, 10:1:2, v/v) was allowed to descend for 3 to 6 days. The test solutions included 3,5-dinitrosalicylic acid in NaOH to show all reducing sugars (Jeanes et al, 1951;McCready et al, 1950), resorcinol for ketoses (Partridge, 1948) and aniline for pentoses (Reid, 1950). Paper chromatograms of the glucose, fructose, and ribose used for these studies were consistent with purity of these sugars.…”

The Chemistry and Biochemistry of Pectic Substances

“…The hydrolases fall into two major categories, those which deesterify (the pectin esterases) and those which split the glycosidic bond (the polygalacturonases). Crude pectinase preparations also hydrolyze the arabinan and galactan present (19,93). It seems likely that this is due to the presence of separate arabinases and galactanases (93), although these have yet to be isolated.…”

The Hydrolysis of Pectic Acid by Purified Fungal Polygalacturonase

“…Hydrolysis apparently occurs by random scission of the glycosidic linkages of pectic acid leading to the accumulation of D -galacturonic acid. By the application of chromatographic methods, compounds intermediate between pectic acid and D-galacturonic acid have been detected during the course of hydrolysis of pectic acid by PG preparations from three different molds ( 6 ) , and also of pectinic acid by commercial pectic enzyme preparations (16). The formation of lower molecular weight products of hydrolysis has been demonstrated, also by the use of ion exchange resins ( 3 ) .…”