Enzymes polymer degradations

Parvinzadeh M, Assefipour R, Kiumarsi A (2009) Biohydrolysis of nylon 6,6 fiber with different proteolytic enzymes. Polym Degrad Stab 94 1197-1205... 

Li, J., Y. Du, J. Yang, T. Feng, A. Li, and P. Chen. 2005. Preparation and characterization of low molecular weight chitosan and chito-oligomers hy a commercial enzyme. Polym. Degrad. Stab. 87 441-448. 

In nature, there are several sources of enzymes that are capable of catalysing the hydrolysis of PHB. The polymer itself is produced by bacteria and occurs in cells as discrete inclusion bodies. These bodies contain the necessary enzymes for degrading the polymer, preventing its build-up in the cell. As well as this, there are numerous bacteria and fungi, many of which are found in the soil, that are capable of secreting the necessary enzymes outside their cell walls, and thus of iiufiating degradation of PHB. 

Cutinase is a hydrolytic enzyme that degrades cutin, the cuticular polymer of higher plants [4], Unlike the oflier lipolytic enzymes, such lipases and esterases, cutinase does not require interfacial activation for substrate binding and activity. Cutinases have been largely exploited for esterification and transesterification in chemical synthesis [5] and have also been applied in laundry or dishwashing detergent [6]. 

Enzymes to degrade crosslinked hydroxypropylated starch derivative and xanthan gum polymer systems are available [158,1246]. Specific enzymes are efficient in reducing the near wellbore damage induced by the starch polymer to eventually return permeabilities to the range of 80% to 98% without the use of acid systems. 

Kolattukudy PE, Crawford MS (1987) The role of polymer degrading enzymes in fungal pathogenesis. In Nishumura S, Vance CP, Doke N (eds) Molecdar determinants of plant diseases. Springer, Berlin Heidelberg New York, p 75... 

Enzymes are used for a variety of therapeutic purposes, the most significant of which are listed in Table 12.8. A number of specific examples have already been discussed in detail within this chapter, including tPA, urokinase, and factor IXa. The additional therapeutic enzymes now become the focus of the remainder of the chapter. Although a limited number of polymer-degrading enzymes (used as digestive aids) are given orally, most enzymes are administered intravenously. 

Zhou M, Takayanagi M, Yoshida Y, Ishii S, Noguchi H (1999) Enzyme-catalyzed degradation of aliphatic polycarbonates prepared from epoxides and carbon dioxide. Polym Bull 42(4) 419 24... 

Tang B, Liaoa X et al (2010) Enhanced production of poly(vinyl alcohol)-degrading enzymes by mixed microbial culture using 1,4-butanediol and designed fermentation strategies. Polym Degrad Stab 95 557-563... 

In order to improve the usability of enzymes, immobilization matrices have been proposed with both environmental decontamination as well as personal detoxification in mind. Effective immobilization methods allow for the preparation of an immobilized enzyme that retains most of its native activity, maintains high operational stability as well as high storage stability. Recent advances in material synthesis using enzymes have allowed the preparation of a variety of bioplastics and enzyme-polymer composites, which involve the incorporation of the enzyme material directly into the polymer. Enzymes stabilized in this way maintain considerable stability under normally denaturing conditions [21]. A number of methods have been used to prepare bioplastic or enzyme-polymer composite materials with OP-degrading enzymes. Drevon Russel described the incorporation... 

Cellulose Cellulose is a straight-chain polymer of glucose units linked by (31-4 bonds. The polysaccharide chains are aligned to form fibrils that have great tensile strength. Cellulases, enzymes that degrade cellulose, are absent in mammals but are produced by some bacteria, fungi and protozoa. 

Degradation can take place by one or both mechanisms. For example, natural polymers such as albumin may be used such proteins are not only water-soluble, but are readily degraded by specific enzymes. The terms degradation, dissolution and erosion are used interchangeably in this chapter, and the general process is referred to as polymer degradation. 

Two steps occur in the microbial polymer degradation process, first, a depolymerisation or chain cleavage step, and second, mineralisation. The first step normally occurs outside the organism due to the size of the polymer chain and the insoluble nature of many of the polymers. Extracellular enzymes are responsible for this step, acting either endo (random cleavage of the internal linkages of the polymer chains) or exo (sequential cleavage of the terminal monomer units in the main chain). 

Poly(s-caprolactone) Poly(e-caprolactone) is a semicrystalline polymer synthesized by anionic, cationic, free-radical, or ring-opening polymerization [94]. It is available in a range of molecular weights and degrades by bulk hydrolysis autocatalyzed by the carboxylic acid end groups. The presence of enzymes such as protease, amylase, and pancreatic lipase accelerates polymer degradation [95], The various methods of preparation of poly(e-caprolactone) nanoparticles include emulsion polymerization, interfacial deposition, emulsion-solvent evaporation, desolvation, and dialysis. These methods and various applications are extensively reviewed [94],... 

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