Degradation of starch

P-amylase, and debranching enzymes. Conversion of D-glucose to D-fmctose is mediated by glucose isomerase, mosdy in its immobilized form in columns. Enzymic degradation of starch to symps has been well reviewed (116—118), and enzymic isomerization, especially by immobilized glucose isomerase, has been fiiUy described (119) (see Syrups). 

StiLrke, /. starch strength intensity size thickness diameter corpulency, -abbau, m. degradation of starch, -art, /. variety of starch. 

The cyclodextrins are produced by the partial degradation of starch followed by the enzymatic coupling of the glucose units into... 

It has been demonstrated [186] that the inclusion of polyacrylamide in either enzymatic or oxidative desizing formulations results in increased pick-up of the liquor by the sized warp yams. Desizing by hydrolytic degradation of starch during the traditional kier-boiling treatment using 3°Be sodium hydroxide liquor at 110 °C is now rarely encountered as it is a slow and expensive process [169]. 

The degrading effect of alkali has been known for some time. Schoch, Wilson and Hudson146 concluded, from the fact that methyl /3-maltoside is stable when heated in 0.1 M caustic soda for considerable periods of time, that alkaline degradation of starch occurs only through the reducing end... 

Myrback, Karl, Products of the Enzymic Degradation of Starch and Glycogen, III, 251-310... 

Karl MyrbAck, Products of the Enzymic Degradation of Starch and Glycogen 252 M. Stacey and P. W. Kent, The Polysaccharides of Mycobacterium tuberculosis 311 R. U. Lemieux and M. L. Wolfrom, The Chemistry of Streptomycin. 337... 

Figure 1. Possible routes for biological and chemical degradation of starch-plastic composites. Note that direct biological degradation of petrochemical-based polymers does not occur. Rather, these polymers must first undergo chemical degradation to form as yet uncharacterized, lower molecular weight intermediates.

Cyclodextrins, products of the degradation of starch by an amylase of Bacillus macerans(1), have been studied in terms of chemical modifications, mainly for the purpose of developing efficient enzyme mimics(2). Not only their unique cyclic structures, but also their ability to form Inclusion complexes with suitable organic molecules, led us to Investigate the total synthesis of this class of molecules(3) We describe here an approach to a total synthesis of alpha(l), gamma(2), and "iso-alpha" cyclodextrin (3). 

Cyclodextrins are formed in the degradation of starch and dextran by the action of cyclodextrin/glucanosyltran-sferases [EC 2.4.1.19]. These enzymes also catalyze so-called acceptor reactions in which the cyclodextrin ring is opened and an acceptor molecule (e.g., glucose) is added to the reducing end of the maltodextrin chain. 

Polymerization in P-cyclodextrin (CD) complexes with monomer offers a route to polymerization, as well as other organic reactions, in water without the need for organic solvents [Ritter and Tabatabai, 2002]. P-Cyclodextrins are toms-shaped, cyclic oligosaccharides obtained by degradation of starch. The hydroxyl groups of the glucose repeat unit of CD are located on the outer surface. This makes the outer surface hydrophilic, whereas the inner surface and cavity are hydrophobic. Water-insoluble monomers become solubilized in water when mixed with CD or CD derivatives because the monomers are absorbed into the cavity. This allows polymerization in aqueous, not organic media, with water-soluble initiators. 

Singh, V., Ali, S. Z. (2000). Aeid degradation of starch. The effect of acid and starch type. Carbohydr. Polym., 41, 191-195. 

Chemoembolization with microencapsulated drugs has been in clinical use since 1978 [6]. Using biodegradable starch microspheres containing anticancer drugs which occlude selected arteries, anticancer drugs can be locally released upon the degradation of starch by serum amylases [333, 334]. 

The degradation of nitrostarch is also considerable, if starch is nitrated by means of a mixed acid composed of nitric and sulphuric acid. On the contrary, application of nitrating mixture consisting of nitric acid and ortho-phosphoric acid makes it possible to obtain a product nearly twice as viscous as that obtained by treatment with a mixture of nitric and sulphuric acid (T. Urbanski and Kapu-Scihski [36]). This shows that the mixture of nitric and phosphoric acid causes less degradation of starch than nitric acid alone or mixed with sulphuric acid. Previously, Berl and Kunze [37] had come to the same conclusion. They found the product of... 

By nitrating different types of starch by means of mixed acid Staudinger and Eilers [43] obtained a product containing 12.5% of nitrogen. Staudinger and Hu-semann [44] followed the degradation of starch during its nitration. 

Manners, D. J., Enzymic Synthesis and Degradation of Starch and Glycogen, 17, 371-430... 

---