Formation mechanisms degradation organisms

The principal degradation mechanism of organic matter in the formation of peats (humic substances included) and leading to the formation of coal, therefore, appears to involve the preferential breakdown of labile biomolecules (carbohydrates, etc.), and the selective preservation of inert and relatively inert (i.e., somewhat degraded) biomolecules (Hatcher and Clifford, 1997). Melanoidin formation may also play some role in the... 

The synthesis and structural analysis of alkaloids leads to the following basic questions Why are alkaloids synthesized in an organism and on which mechanism is alkaloid formation and degradation dependent in the life... 

Information on the products of the oxidation of caronaldehyde is limited. Colville and Griffin (2004) have developed a mechanism for the oxidation of A -carene using the protocols for the MCM by Jenkin et al. (1997). Their main aim was to provide information to understand the formation of secondary organic aerosol, so that they were interested in the formation of condensable intermediates rather than in the complete degradation pathway. They showed that initial abstraction by OH of the aldehydic H or photolysis, followed by reaction with O2, both lead to decarboxylation and formation of a peroxy radical similar to that formed in the initial stages of pinonaldehyde oxidation. They did not, however, pursue the mechanism further. 

Alkaline Degradation. At high pH, sucrose is relatively stable however, prolonged exposure to strong alkaU and heat converts sucrose to a mixture of organic acids (mainly lactate), ketones, and cycHc condensation products. The mechanism of alkaline degradation is uncertain however, initial formation of glucose and fructose apparendy does not occur (31). In aqueous solutions, sucrose is most stable at —pH 9.0. 

Antioxidants are used to retard the reaction of organic materials with atmospheric oxygen. Such reaction can cause degradation of the mechanical, aesthetic, and electrical properties of polymers loss of flavor and development of rancidity ia foods and an iacrease ia the viscosity, acidity, and formation of iasolubles ia lubricants. The need for antioxidants depends upon the chemical composition of the substrate and the conditions of exposure. Relatively high concentrations of antioxidants are used to stabilize polymers such as natural mbber and polyunsaturated oils. Saturated polymers have greater oxidative stabiUty and require relatively low concentrations of stabilizers. Specialized antioxidants which have been commercialized meet the needs of the iadustry by extending the useflil Hves of the many substrates produced under anticipated conditions of exposure. The sales of antioxidants ia the United States were approximately 730 million ia 1990 (1,2). 

There are several examples in which metabolites that toxify the organism responsible for their synthesis are produced. The classic example is fluoroacetate (Peters 1952), which enters the TCA cycle and is thereby converted into fluorocitrate. This effectively inhibits aconitase—the enzyme involved in the next metabolic step—so that cell metabolism itself is inhibited with the resulting death of the cell. Walsh (1982) has extensively reinvestigated the problan and revealed both the complexity of the mechanism of inhibition and the stereospecihcity of the formation of fluorocitrate from fluoroacetate (p. 239). It should be noted, however, that bacteria able to degrade fluoroacetate to fluoride exist so that some organisms have developed the capability for overcoming this toxicity (Meyer et al. 1990). 

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