Biological degradation enzymes

The first step in the biological degradation of histidine is formation of a 4-methylideneimidazol-5-one (MIO) by cyclization of a segment of the peptide chain in the histidine ammonia lyase enzyme. Propose a mechanism. 

Mueller RJ (2006) Biological degradation of synthetic polyesters - enzymes as potential catalysts for polyester recycling. Process Biochem 41 2124-2128... 

Cheng TC, Rastogi VK et al. (2003). Compatibihty of CW agent degrading enzymes with disinfectants and foams. Proceedings of the joint service sientific conference on chemical biological defense research. Hunt Valley, USA... 

A suggested treatment involves the use of OP-degrading enzymes. Enzymes are biological catalyst proteins that can be used to detoxify both trace and large quantities... 

Many biological cells contain degradative enzymes (proteases) that catalyze the hydrolysis of peptide linkages. In the intact cell, functional proteins are protected from these destructive enzymes because the enzymes are stored in cell organelles (lysosomes, etc.) and released only when needed. The proteases are freed upon cell disruption and immediately begin to catalyze the degradation of protein material. This detrimental action can be slowed by the addition of specific protease inhibitors such as phenylmethyl-sulfonyl fluoride or certain bioactive peptides. These inhibitors are to be used with extreme caution because they are potentially toxic. 

Biological degradation requires that fungi or microorganisms can attack the polymer with their enzymes. This happens efficiently with very few polymers (because these enzymes do not exist) and is, of course, the reason that they are used people tolerate ugly plastic window frames because they don t rot. 

Tokiwa, Y. Suzuki, T. (1977). Microbial-degradation of poly esters 3. Purification and some properties of polyethylene adipate-degrading enzyme produced by Penicillium sp strain 14-3. Agricultural and Biological Chemistry, 41, 265-74. 

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