Oxidative detoxification

Sutherland TD, I Home, RJ Russell, JG Oakeshott (2002) Gene cloning and molecular characterization of a two-enzyme system catalyzing the oxidative detoxification of 3-endosulfan. Appl Environ Microbiol 68 6237-6245. 

Saraiva LM, Vicente JB, Teixeira M (2004) The role of the flavodiiron proteins in microbial nitric oxide detoxification. Adv Microb Physiol 49 77-129 Schirch V, Szebenyi DME (2005) Serine hydroxymethyltransferase revisited. Curr Opin Chem Biol 9 482-487... 

Some microbial pathogens can circumvent the defensive response of plants by biotransforming the antimicrobial stilbenoids in a multi-step oxidative detoxification process [106], Research has shown that the pathogenicity of B. cinerea strains is positively correlated with these fungi s production of blue-copper oxidases known as stilbene oxidases or laccases [127,128]. These enzymes are polyphenol oxidases capable of catalyzing the oxidation and polymerization of numerous phenolic substrates [129,130,131,132]. It has been shown that 1 is readily transformed in the presence of B. cinerea culture medium filtrates that contain laccases [107]. Recently, six resveratrol dimers (restrytisols A-C... 

Molecular oxygen is used in a variety of oxidative detoxification reactions aromatic hydroxylation aryl oxidation O- and M-deaUcylation deamination and sulfoxidation. These reactions either modify functional groups or add oxygen to the foreign compound, forming metabolites that lack pharmacological activity and which are more rapidly eliminated in the urine because of increased water solubility. 

Yang Y, Szafraniec LL, Beaudry WT, Rohrbaugh DK (1990) Oxidative detoxification of phosphonothiolates. J Am Chem Soc 112 6621-6627. 

Topical Exposure. Dosing of female house fly females with five monoterpenoids yielded toxic effects when applied alone at high doses. d-Limonene was the most active of the five (Table I). Use of the synergist piperonyl butoxide enhanced the activity of d-limonene, pulegone, and linalool considerably, by 17, 21, and >14 fold, respectively. These results indicate that those three terpenoids insecticidal activity is expressed more fully when the oxidative detoxification process is inhibited. It is not surprising that flies can detoxify them rapidly, considering the relatively simple hydrocarbon structures of the monoterpenoids. 

Importantly, product selectivity in the heterogeneous systems is the same as in acetonitrile, eq 1, namely that no sulfoxide overoxidation to sulfone is observed in these systems within the limits of instrumental detection. This is very important for mustard gas (HD) oxidative detoxification, because the sulfoxide, HD(0) , is significantly less toxic than the sulfone, HD(0)2 . Since these systems are heterogeneous, their full kinetic evaluation is not possible. However, they are very similar to homogeneous ones because the same product (CEESO) and selectivity ( 1(X)% CEESO) are observed both halide and NO3 are required for activity and Cu(II) is a highly active cocatalyst. These similarities suggest that the key features of the mechanisms in the two types of media are also very similar. 

While progress is being made in this area of plant metabolism, difficulties associated with the isolation of plant microsomal preparations active in the utilization of other herbicide substrates, and with the purification of the active mfo enzymes themselves, are still to be resolved. Consequently, only slow progress has been made on the identification of specific mfo polypeptides suitable as candiates for gene transfer studies. Such studies are aimed at manipulating crop plants for herbicide resistance based on enhanced oxidative detoxification. 

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