Camphor degradation

These observations suggest that the oxidative reactions occurring on toxaphene are similar in nature to the system described for camphor degradation (M). It is unfortunate that the above experiments could only be conducted with washed intact cells as cell-free preparations in all cases did not exhibit metabolic capabilities. The reason for this phenomenon has not been found, but to our knowledge no other research group has been able to demonstrate pesticide degrading activities of such oxygenase systems in cell-free preparations. 

Hartline, R.A. and I.C. Gunsalus, 1971. Induction speci city and catabolite repression of the early enzymes in camphor degradation by Pseudomonasputida. J. BacterioL, 106 468-478. 

The initial hydroxylation in the degradation of some terpenes the ring methylene group of camphor by Pseudomonas putida (Katagiri et al. 1968 Tyson et al. 1972 Koga et al. 1986), and the isopropylidene methyl group of linalool by a strain of P. putida (Ullah et al. 1990). 

Cellulose nitrate (Celluloid) 1850 Moulding material, paints, glues, coatings, photographic films, varnishes Camphor, phthalate esters High flammability and degradability, with production of nitrogen dioxide... 

First, the effects of aerobic and anaerobic culture conditions on toxaphene degradation were studied with washed P. putida cells grown on camphor and incubated with no readily usable carbon source. The radioactivities remaining in water after extraction with n-hexane were used as an indicator of metabolic activity. This was further extracted with ethyl acetate after acidification to divide this "total polar metabolites" fraction into aqueous buffer phase and ethyl acetate phase, i.e., the total polar metabolites reported refer to summation of the aqueous buffer and ethyl acetate soluble phases (Table 4). All radioactivities have been corrected by zero time controls and autoclaved 8 hr controls are included in each experiment. 

Hydroxy acids provide characteristic mono or diol synthons whereas amino acids are the natural source for 1,2-amino alcohol fragments. A stereogenic center in either configuration, with methyl brandling, may be obtained from (S)-3-hydroxy-2-methylpropanoic acid, whereas quaternary dimethyl-substituted carbons with adjacent stereogenic centers are available from the degradation of camphor or a-pincnc. 

The biosynthesis of monoterpenoids and camphor has been described by several authors (108-llU). Ruzicka (115,116) proposed a unified biogenetic scheme for terpenes. The biosynthetic building blocks for these terpenes are iso-prene units. The biosynthetically active isoprene units are isopentenyl pyrophosphate [l] and dimethyl allyl pyrophosphate [2] the compounds that are derived from acetate via mevalonic acid (Scheme V). Geranyl pyrophosphate [3] is the C-10 precursor for the terpenes (117). Banthorpe and Baxendale (ll8) confirmed the biosynthetic pathway of (iamphor via acetate mevalonate by conducting degradation study of camphor, biosynthesized from l c labelled mevalonic acid. The biosynthesis of camphor is summarised in Scheme VI. 

Unless stored in perfect conditions, an object made of celluloid can degrade, giving off a smell of camphor (which smells like moth balls), and turning sticky or powdery (Fig. 13.3). 

The structure of camphoronic acid (a degradation product of the terpene camphor) was established by the following synthesis ... 

In order to determine the structure of the photochemical rearrangement product of carvone camphor in methanol, and to prove its structure, the research team of T. Gibson subjected the bicyclic carboxylic acid product to a degradation sequence, which commenced with the HVZ reaction, followed by dehydrohalogenation, dihydroxylation and glycol cleavage. 

The understanding of the degradation of natural products such as camphor has been greatly enhanced by understanding the catalytic cycle of the cytochrome P-450 enzyme P-450cam in structural detail.3,4 These enzymes catalyze the addition of 02 to nonactivated hydrocarbons at room temperatures and pressures - a reaction that requires high temperature to proceed in the absence of a catalyst. O-Methyltransferases are central to the secondary metabolic pathway of phenylpropanoid biosynthesis. The structural basis of the diverse substrate specificities of such enzymes has been studied by solving the crystal structures of chalcone O-methyltransferase and isoflavone O-methyltransferase complexed with the reaction products.5 Structures of these and other enzymes are obviously important for the development of biomimetic and thus environmentally more friendly approaches to natural product synthesis. 

The oxidation of racemic fenchone by a Corynebacterium sp.[7<>1 (reclassified as Mycobacterium rhodochrous), an organism which grows at the expense of either (+)- or (-)- camphor, has also been reported. This was shown to lead, in a 45% yield, to a 90/10 mixture of 1,2 and 2,3-fencholides, as shown in Fig. 16.5-12. This result contrasts with the chemical oxidation of fenchone with peracetic acid, where 2,3-fencholide is the major product in a 40/60 mixture. Accumulation of these lactones is a priori surprising as compared with the total degradation of the structurally similar camphor substrate. However this may simply be due to the fact that this lactone, unlike that formed from camphor, is chemically stable in the medium. Of course, one has also to assume that, here again, the strain is devoid of any lactone hydrolase. This bioconversion was the first gram-scale preparative report... 

Similarly, it has been shown that 1,8-cineole and 6-oxo-cineole are degraded via the scheme shown in Fig. 16.5-13[71]. As in the case of camphor, the first step involves a... 

Pseudomonas putida CAM - camphor ETBE, TAME Incomplete MTBE degradation to TBA [58]... 

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