Glucans starch degradation

Enzymes should be added to the feed together with the pre-mix. Granulated enzyme products may readily be mixed with feed components, as they are based on normal feed components such as wheat or soy grits. A wide range of enzyme products are available. Enzyme products should contain specific enzyme activities necessary to degrade specific substances such as glucans, starch, protein, pectin-like polysaccharides, phytic acid, raffinose, stachyose, hemicellulose, and cellulose. 

Figure 10-5 Diagrammatic Representation of Amylopectin Structure. Lines represent a-D-glucan chains linked by 1,4-bonds. The branch points are 1,6-a glucosidic bonds. Source From J.J. Marshall, Starch Degrading Enzymes, Old and New, Starke, Vol. 27, pp. 377-383, 1975.

Red algae enzymes in the starch degradation pathway (e.g., a-1,4-glucan lyase and others)... 

Similarly, the choice of enzymes in pathway design is of importance. In the case of the conversion of cellulose to starch, cellobiose phosphorylase and a-glucan phosphorylase are responsible for reversibly eonverting from eello-biose to amylose or vice versa. It was found that a-gluean phosphorylase from potato is a key enzyme to drive the reaction toward starch synthesis. In contrast, the same enzyme from Clostridium thermocellum eannot generate amylase from cellobiose because it prefers the starch degradation direetion. ... 

Functionally, starch can be considered as a polysaccharide synthesized in a manner permitting its efficient degradation. Hence, biosynthesis of the starch granule is a delicate balance between efficient packing of the glucan chains and the possibility of breaking these structures at degradation. To complete this enzymatically catalyzed process in the potato tuber, a multitude of different enzyme activities are required. 

S. Yu, T. Ahmad, L. Kenne, and M. Pedersen, a-1,4-Glucan lyase, a new class of starch glycogen degrading enzyme. 3. Substrate specificity, mode of action, and cleavage mechanism, BBA General Subjects, 1244 (1995) 1-9. 

Pullulanase Enzyme degrading pnUnlan, a branched starch pullulanase catalyzes the hydrolysis of the a-l,6-glncosidic linkage in a-glucans. Pullulanase preferentially hydrolyzes pnUnlan while isoamylase has a preference for glycogen and amylopectin. See WaUenfels, K Bender, H and Rached, J.R., Pnllnlanase from Aerobacter aerogenes production in a cell-bound state. Pnrification and properties of the enzymes, Biochem. Biophys. Res. 

Beta amylase is an exoenzyme that degrades amylose chains from the nonreducing end, to liberate maltose. The official notation of this enzyme is (1 — 4)-a-D-glucan maltohydiolase, EC 3.2.1.2. The changes as a function of time in the beta-amylolytic index (a percents of the convernon into maltose) for com starch is shown in Fig. 19. A small increase in the case of dextrinization at lower temperatures was interpreted as the result of cleavage of hydrogen bonds, which makes some r ons of hydrolyzed material more easily accessible to enzymes. ... 

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