Enzymes pseudomonas-sensitive

Pefloxacin (33) is the N-methyl analogue of norfloxacin (58) and is at least partly converted to it by metabolic enzymes in vivo. It has been launched in France for the treatment of a number of infections including those caused by sensitive strains of Pseudomonas aeruginosa. It can be synthesized starting with the Gould-Jacobs reaction of 3-chloro-4-fluoroaniline (28) and diethyl ethoxymethylenemalonate in an addition-elimination sequence leading to 29 which undergoes... 

As mentioned above, Met(0) must be converted to Met before it can be incorporated into proteins. There are a wide variety of organisms that have been shown to be capable of enzymatically reducing Met(O) residues. The enzymatic reduction of free Met(O) to Met has been observed in yeast , E. cofi - , Pseudomonas , plants and animal tissues . The enzyme from E. coli has been purified about 1100-fold using a newly developed very sensitive assay . The assay involves first the conversion of [ S]Met(0) to [ S]Met by the Met(O) reductase followed by the measurement of [ S]Met-tRNA after enzymatic acylation of tRNA. Since Met(O) is not a substrate for the acylation reaction , the amount of [ S]Met-tRNA formed is proportional to the amount of [ S]Met(0) converted to [ S]Met. The assay is sensitive to Met levels of less than 1 pmol. 

The Aeromonas and Pseudomonas enzymes have been studied in detail. Both enzymes are very sensitive to sulfhydryl and carbonyl inhibitors and possess 4 moles of pyndoxal 5 -phosphate bound in aldimine linkages to -amino groups of lysine residues. They nave similar substrate specificities and, in... 

Pseudomonas and Azotobacter transhydrogenases was provided by Cohen and Kaplan (17) and by van den Broek et al. [19), respectively, who showed that inactivation by heat treatment could be reversed by addition of FAD. FAD could not be replaced by FMN. Reduction of the enzyme with either NADH or NADPH largely increased the heat sensitivity, whereas oxidized nicotinamide nucleotides or FAD had the opposite effect (17, 19). The number of flavins per 50,000-dalton molecular weight was calculated to be 0.58 to 1.1 (17). 

Class III enzymes are the plasmid-mediated TEM -type yS-lactamases which have approximately equal activity against penicillins and cephalosporins they are sensitive to inhibition by cloxacillin and resistant to inhibition by p-chloromercuribenzoate. They are commonly found in strains of E. coli and Pseudomonas, as well as Haemophilus, Neisseria, Salmonella and Shigella. The SHV-1 and HMS enzymes also belong to this class of enzyme and together they are the most commonly encountered y3-lactamases worldwide. 

Another example of monoene isomerization is a cis-trans isomerase identified in some aerobic bacteria that convert oleic acid to elaidic acid as a protective mechanism. This cis-trans isomerase is constitutively present in Pseudomonas (35) and converts oleic add to elaidic acid to alter its membrane permeability for protection from growth inhibitors such as toxicants (36) or extremes in ambient temperature (37). The isomerase exhibits regiospecificity, where the active site of the enzyme penetrates to a spedfic depth in the membrane. Thus, enzyme activity is sensitive to changes in membrane fatty acid composition and fluidity (35) and does not require ATP or cofactors such as NAD(P)H. 

For some enzymes, such as Pseudomonas sp. lipase (PSL), the liberated acid does not present any problems, but others like CRL are more sensitive and require more protection. For instance, when acetic anhydride is used, the Uberated acetic acid may lead to a decrease of the pH in the micro-environment of the enzyme, thus leading to a depletion of activity and selectivity. The CRL-catalyzed resolution of the bicyclic tetrachloroalcohol shown in Scheme 3.5, using acetic anhydride as acyl donor, initially proceeded with only moderate selectivity (E = 18). Addition of a weak inorganic or (preferably) organic base such as 2,6-lutidine which functions... 

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