Metabolic oxidation reactions

The free energy changes in metabolic oxidation reactions serve several purposes. Part of this energy appears as heat flows that maintain body temperature and disperse energy to the surroundings. Another portion of the energy... 

Jurva, U., Wikstrom, H. V., and Bruins, A. P. (2000). In vitro mimicry of metabolic oxidation reactions by electrochemistry/mass spectrometry. Rapid Commun. Mass Spectrom. 14 529-533. 

Metabolic oxidation reactions may occur to the side chains of sulfor-containing residues, similar to that observed for in vitro chemical instability. Methionine can be oxidized to the sulfoxide, whereas metabolic oxidation of cysteine residues forms a disulfide. Metabolic reductive cleavage of disulfide bridges in proteins may occur, yielding free sulfhydryl groups. 

BOTH RIBOSE-5-P AND NADPH ARE NEEDED BY THE CELL In this case, the first four reactions of the pentose phosphate pathway predominate (Figure 23.37). N/VDPH is produced by the oxidative reactions of the pathway, and ribose-5-P is the principal product of carbon metabolism. As stated earlier, the net reaction for these processes is... 

The third reaction of this cycle is the oxidation of the hydroxyl group at the /3-position to produce a /3-ketoacyl-CoA derivative. This second oxidation reaction is catalyzed by L-hydroxyacyl-CoA dehydrogenase, an enzyme that requires NAD as a coenzyme. NADH produced in this reaction represents metabolic energy. Each NADH produced in mitochondria by this reaction drives the synthesis of 2.5 molecules of ATP in the electron transport pathway. L-Hydroxyacyl-... 

The results presented above indicate that the previously unknown head-to-tail polymerization is the major reaction product of the iminium methide species. To investigate the generality of this reaction, we next studied a neutral ene-imine species shown in Scheme 7.9.48 As illustrated in this scheme, the generation of this reactive species requires quinone reduction followed by elimination of acetic acid. The ene-imine is structurally related to the methyleneindolenine reactive species that is a metabolic oxidation product of 3-methylindole (Scheme 7.9).57 59... 

Volume I). The most rapid metabolic deactivating reaction is oxidation to the bioinert C15 oxo prostaglandins. Converting the latter to a tertiary methyl carbinol led to the desired orally active gastric antisecretory agents. 

Turning to the additional metabolism that needs extra controls there was little change in basic prokaryote reductive metabolism in the cytoplasm from anaerobes to aerobes but as stated above there were added several oxidative reactions and... 

Guengerich FP, Geiger LE, Hogy LL, et al. 1981. In vitro metabolism of acrylonitrile to 2-cyanoethylene oxide, reaction with glutathione, and irreversible binding to proteins and nucleic acids. Cancer Res 41 4925-4933. 

Metal ions play an important role in several of these oxidative reactions as well as in biological dioxygen metabolism. As an example, copper(II) acetate and hydrogen peroxide have been used to produce a stable oxidizing agent, hydroperoxy copper(II) compound. The same oxidation system is also obtained from copper(II) nitrate and hydrogen peroxide (Eq. 1) [103] but requires the neutralization of ensuing nitric acid by potassium bicarbonate to maintain a pH 5. 

Aromatic amines are initially metabolized by aromatic and A -hydroxylation (oxidation reactions) and Y-acetylation. Following aromatic ring hydroxylation, the ring structure may be further conjugated with glucuronic acid or sulfate (Parkinson 1996). N-hydroxylation results in the potential methemoglobin-generating metabolite,... 

Roberts ES, Vaz AD, Coon MJ. Catalysis by cytochrome P-450 of an oxidative reaction in xenobiotic aldehyde metabolism deformylation with olefin formation. Proc Natl Acad Sci USA 1991 88(20) 8963-8966. 

---