Amylases starch degradation

Of particular importance for modifications of starch are the enzyme degradation products such as glucose symps, cyclodextrins, maltodextrins, and high fmctose com symps (HFCS). Production of such hydrolysis products requites use of selected starch-degrading enzymes such as a-amylase,... 

Fungal amylase has relative low heat stability and its major application is in the baking industry to supplement the variable activity of amylase present in wheat flour. Bacterial amylase is much more heat stable and it is used in brewing, starch degradation, alcohol, textile, and detergent industries. The organisms commonly used for the commercial production of a-amylase include ... 

Figure 4-19 Schematic Representation of the Action of Starch-Degrading Enzymes. (A) Amylose and amylopectin, (B) action of a-amylase on amylose and amylopectin, (C) action of a debranching enzyme on amylose and amylopectin, (D) action of amyloglucosidase and debranching enzyme on amylose and amylopectin. Source Reprinted from H.S. Olsen, Enzymic Production of Glucose Syrups, in Handbook of Starch Hydrolysis Products and Their Derivatives, M.W. Kearsley and S.Z. Dziedzic, eds., p. 36, 1995, Aspen Publishers, Inc.

With -amylase, completely degrades starch to maltose. (Use of -amylase alone will result in the accumulation of -limit dextrins.)... 

Many starch-degrading enzymes have been investigated electro-phoretically in attempts to confirm their homogeneity, for example, alpha-amylase, heta-amylase, phosphorylase, and pullulanase. ... 

In this connection it should be pointed out that maltotriose, a trisaccharide with two maltose linkages, is not attacked by j3-amylase, but is fermented by common yeasts. This has possibly caused some confusion in the chemistry of starch degradation. 

Some of the enzymes discussed above have been detected in filtered water samples free of particulate matter. These include the phosphatases and the starch-degrading amylases. Generally, free enzymes appear to be more abundant in sediments than in the water column (Kim and Zobell, 1972), but at times some of them, such as alkaline phosphatase, can be as active as their particle-bound forms (Berman, 1970). Dissolved extracellular enzymes are presumably excreted by various microorganisms, or perhaps are released during cell degradation or lysis. 

Due to the lack of nonreducing glucose residues in the molecule, CDs are not substrates of the exo-type starch-degrading enzymes. In fact, they are potential inhibitors of some amylolytic enzymes such as P-amylase and pullulanase. 

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