Metabolism, chemical transformation

Coenzymes are densely functionalized organic cofactors capable of catalyzing numerous diverse chemical reactions. Nature exploits the intrinsic chemical reactivity of these molecules to extend the chemical fimctionaUty of enzymes well beyond the reactivity of the coded amino acids. When these constituents are incorporated via covalent or non-covalent interactions into coenzyme-depen-dent enzymes, the inherent reactivity of the co enzyme is augmented and directed to effect chemical transformations with substrate and product selectivities, rates, and yields that are unachievable by either the protein or coenzyme alone. Thus, coenzymes play a critical role in the execution of a large number of essential metabolic processes. 

Amino acids have a larger role to play in life than serving as the building blocks of proteins, itself an absolutely critical role. Specifically, several of the amino acids are key metabolic precursors to families of products. That is, these amino acids are the starting point for one or a series of chemical transformations, all catalyzed by... 

Xenobiotic Metabolism The chemical transformation of compounds foreign to an organism by various enzymes present in that organism. 

The chemistry of DNA damage is diverse and complex. The cellular response to this damage includes a wide range of enzymatic systems that catalyze some of the most interesting chemical transformations in DNA metabolism. We first examine the effects of alterations in DNA sequence and then consider specific repair systems. 

Pseudomonas. These gram-negative bacteria are a diverse group of microbes that inhabit plants, water, and soil. Pseudomonads are metabolically versatile, capable of carrying out chemical transformations, mineralization of organic compounds, and colonization on plant roots (16). The use of Pseudomonads strains in the clean up of chemical wastes and oil spills has drawn considerable attention. 

METABOLISM. The chemical transformations occurring in an organism. from the lime a nutrient substance enters it until it has been utilized and the waste products eliminated In animals and humans, digestion ami absorption are primary steps, followed by complicated series of degradations. syntheses, hydrolyses, and oxidations, in which agents such as enzymes, bile acids, and hydrochloric acid take part. These transformations are often localized with respect to organs, tissues, and types ol cells involved. 

For many elements, the concentration of a species in a given body of water can be predicted by abiotic chemical reactions such as protolysis, precipitation, complexation, redox, and sorption. Aquatic organisms can influence the concentration of compounds directly by metabolic uptake, transformation, storage, and release. Aquatic organisms may also cause chemical reactions by changing the concentrations of solutes which are important in abiotic equilibria. 

The triazine herbicides can be divided into four different structural classes chlorotriazines, methylthiotriazines, methoxytriazines, and atypical or asymmetrical triazines. The chlorotriazine group includes atrazine, simazine, pro-pazine, terbuthylazine, and cyanazine. The methylthiotriazine group includes ametryn, prometryn, and terbutryn. The methoxytriazine group will include prometon and secbumeton. Hexazinone and metribuzin were chosen to represent the atypical triazine group. The plant metabolism of the most researched member of each triazine group will be discussed in detail to cover all major biological and chemical transformations reported in the literature. 

Metabolism, the sum of all chemical transformations taking place in a cell, is a highly coordinated network of activities in which many multi-enzyme systems and pathways are involved. The purposes of this network can be summarized as follows ... 

It is chemical in essence terran living systems contain molecular species that undergo chemical transformations (metabolism) under the direction of molecules (enzyme catalysts) whose structures are inherited, and heritable information is itself carried by molecules. 

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