Pectin enzymic deesterification

Other pectins with degree of esterification of about 10, 30 and 40% (Table I) were obtained by enzymic deesterification of the initial preparation. An orange pectinesterase was used and the pH of the reaction was 6 in order to avoid concurrent base-catalyzed saponification. The action of plant pectinesterase is known (16-18) to result in a blockwise arrangement of free carboxyl groups in the pectic molecules. The enzymic preparation does not contain depolymerase activities as shown by the constancy of the intrinsic... 

When cell-wall fragments are incubated in molar NaCl, ionically bound proteins are released into the incubation medium. All investigated crude cell extracts deesterified Citrus pectin (Table 2) but the deesterification rates were clearly higher when the enzymes were still bound to the cell walls, indicating a major loss of activity during the solubilization process. 

The behaviour of the added alkali cations is different. Na and K enhance the deesterification and the differences in the interaction of both cations at the separate reactions are inessential. The use of these ions in the deesterification of highly esterified pectin in either enzyme or chemical method shows that they only enhance the hydrolysis. Since in the investigated case they cannot influence the equilibrium (6), the enhancement of the hydrolysis leads to faster exhausting of the reactable -COOCH3 groups and thus is reduced the rate of the competitive ammonolysis. 

This study reports on the production of pectic enzymes and partial characterization of polygalacturonases produced by Candida boidinii. Candida boidinii belongs to the so called methylotrophic yeasts with famous utilization of methanol. Pectin, the natural substrate of pectic enzymes complex, can serve for microorganisms as a C - source by two different ways after deesterification with pectinesterase as methanol and after hydrolytic cleavage with... 

Pectinesterase action was first reported in 1840 by Fremy (56). He noted that the addition of carrot juice to a pectin solution caused formation of a gel. This gel was produced by the enzymatic deesterification of pectin followed by precipitation of the resulting polygalacturonic acid as calcium pectate 20), Various names such as pectin meth-oxylase and pectin methyl esterase have been applied to the enzyme, but pectinesterase is the preferred trivial name (57). 

Samples of pectins with varying degrees of esterification (0-60%) were obtained from this preparation by deesterification with alkali and with enzyme. The main characteristics of these samples are indicated in Table I. It is likely that the action of alkali leads to pectic molecules in which free and methyl esterified carboxylic acids are randomly distributed (1 ). The temperature was chosen in order to minimize chain-cleavage by B-elimination ( ) and intrinsic viscosity measurements of the samples (sodium form in 0.1 M NaCl) showed that the degradation was minimal (15). 

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