Initial step in degradation

Stoeckle, M. Y. (1992). Removal of a 3 non-coding sequence is an initial step in degradation of gro alpha mRNA and is regulated by interleukin-1. Nucleic Acids Res. 20, 1123-1127. 

Fig. 3. Initial steps in the aerobic degradation of naphthalene, as a representative multiringed aromatic, and toluene. The different initial steps of toluene...

Weber R, S Yoshida, K Miwa (2002) PCB destruction in subcritical and supercritical water—evaluation of PCDF formation and initial steps of degradation mechanisms. Environ Sci Technol 36 1834-1844. 

Haddock JD, JG Ferry (1993) Initial steps in the anaerobic degradation of 3,4,5-trihydroxybenzoate by Eubacterium oxidoreducens characterization of mutants and role of 1,2,3,5-tetrahydroxybenzene. J Bacterial 175 669-673. 

Best DJ, NC Floyd, A Magalhaes, A Bnrfield, PM Rhodes (1987) Initial steps In the degradation of alpha-pinene by Pseudomonas fluorescens NCIMB 11671. Biocatalysis 1 147-159. 

The initial steps in the degradation of 2 -methyl-4-methoxystyrene (tran -anethole) by a strain of Arthrobacter aurescens are comparable to those already noted, except that the epoxide is hydrolyzed to a diol to produce 4-methoxybenzoate (Shimoni et al. 2002). 

Chlorobenzoates may be formed during the initial steps in the aerobic degradation of PCBs, and their further metabolism illustrates a number of pathways. There are several reactions that carry out dehalogenation including dioxygenation, hydrolysis, and reduction. 

A mutant strain of Alcaligenes eutrophus was used (Reiner and Hegeman 1971) to demonstrate that the initial step in the metabolism of 4-fluorobenzoate involves 1 2 dioxygenation to 4-fluoro-1,2-dihydrodihydroxybenzene-l-carboxylate. 4-Fluorobenzoate may be used for growth by several bacteria, and metabolites produced by a strain of Pseudomonas sp., which was also able to degrade... 

Methyl ketones are degraded to the next lower carboxylic acid by reaction with hypochlorite or hypobromite ions. The initial step in these reactions involves base-catalyzed halogenation. The a-haloketones are more reactive than their precursors, and rapid halogenation to the trihalo compound results. Trihalomethyl ketones are susceptible to alkaline cleavage because of the inductive stabilization provided by the halogen atoms. 

A lot of research about the metabolism of PPCPs in clinical practice has been conducted under the auspices of pharmacology. As alluded to above, drug metabolism in the body results in the breakdown of the compound into metabolites that are chemically simpler, just like what chemical and biological processes attain in the environment. When such breakdown occurs in the environment, it is typically referred to as degradation. Initial steps in the degradation process in the environment also involves modification of the active sites (similar to phase I processes in our bodies) but... 

As in thermal degradation, the process begins with an initiation step, in this case the formation of radicals where X denotes a source of free radicals, such as polymer chains, which then react with atmospheric oxygen ... 

Isoleucine is both ketogenic and glucogenic, because its metab olism yields acetyl CoA and propionyl CoA. The first three steps in the metabolism of isoleucine are virtually identical to the initial steps in the degradation of the other branched-chain amino adds, valine and leucine (see Figure 20.10). 

Pyrolysis is the thermal degradation of an organic material in the absence of oxygen, also the initial step in combustion and gasification. The products formed in the pyrolysis are a solid residue called char, a liquid called bio-oil, and uncondensed gases. The process can be optimized for maximal bio-oil production. Important requirements in this optimization are the following ... 

The oxidation of cyclohexane is accompanied by the oxidative degradation of the products. In other words, the products themselves undergo metal-initiated radical chain oxidation. For this reason oxidation is normally carried out at low conversions when the selectivity to the desired products is high. The catalysts used are a mixture of hydrocarbon soluble carboxylate salts of Co2+ and Mn2+ or Cr3+. Due to the better solubility properties, salts of long-chain carboxylic acids such as 2-ethyl hexanoic or naphthenic acids are favored. As already mentioned, the primary role of the metal ions is to act as catalysts for the initiation steps. In other words, the metal ions undergo redox reactions with 8.9 to give 8.10 and 8.11. 

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