Glycosidic bonds degradation

The term represents the kinetic efficiency of the enzyme. Table 14.4 lists turnover numbers for some representative enzymes. Catalase has the highest turnover number known each molecule of this enzyme can degrade 40 million molecules of HgOg in one second At the other end of the scale, lysozyme requires 2 seconds to cleave a glycosidic bond in its glycan substrate. 

At temperatures above Tm, chemical and enzymatic degradation of microbial exopolysaccharides is enhanced. The apparent enhanced stability of microbial exopolysaccharides in their ordered confirmation is thought to be due to the glycosidic bonds in the backbone of the polymer which raises the activation energy. This restricted movement would also restrict access of enzymes and chemicals to the backbone. 

Alkali-catalyzed cleavage of glycosidic bonds of glycosaminoglycur-onates occurs by way of -elimination.223 By proper choice of the experimental conditions, it seems possible to achieve a controlled degradation of heparin by -elimination, producing fragments apparently preserving... 

For three endo-D-galacturonanases, isolated from the culture filtrate of Coniothyrium diplodiella,114-116 that differed in the extent of degradation of sodium pectate, a 50% decrease of viscosity of the substrate solution corresponded to the splitting of 3, 4, and 10% of the glycosidic bonds, respectively. A similar difference was found between two endo-D-galacturonanases isolated from tomatoes117 one... 

In the course of degradation of nonesterified and low-esterified substrates by pectate lyases, the glycosidic bonds can be split either at random or terminally, starting from the reducing end of the molecule. On the other hand, in the course of splitting of highly esterified substrates by pectin lyases, only the random-action pattern is operative. So far, no pectin lyase is known that can split the glycosidic bonds terminally. 

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