Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.25.1 (proteasome)
 28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

From concrete debris of a demolished herbicide production plant several Gram-negative bacterial strains were isolated, which exhibit metabolic capabilities for the degradation of 2,4-dichlorophenol (DCP)l), 4-chloro-2-methylphenol (MCP) and 4-chlorophenol (4-CP), while 2-chlorophenol (2-CP) was degraded at a slower rate. Degradative activity was inducible and was impeded by adding of 100 mg/l of chloramphenicol to growing cultures. The strains displayed alkaliphilic properties with optimum DCP/MCP degradation at pH values around 8.5-9.5; activity was observed up to pH values of 11. Degradation was most likely complete according to chlorine balances; formation of intermediary products was observed with MCP some time. Specific activity of up to 380 mumol/h.g dry mass was found within the concentration range of 10-20 mg/l DCP; higher concentrations retarded the activity with complete inhibition at 200-400 mg/l. Some of the strains carry plasmids whose presence was not unambiguously correlated to the degradative properties. Ribotyping revealed a high degree of relationship between the strains. Preliminary taxonomic investigations showed close relationship to Ochrobactrum anthropi.
 ...
PMID:Degradation of various chlorophenols under alkaline conditions by gram-negative bacteria closely related to Ochrobactrum anthropi. 979 48

Bacterial strains were isolated from the concrete rubble of a demolished herbicide production plant. The predominant feature of these strains was the etherolytic cleavage of 4-(2,4-dichlorophenoxy)butyric acid (DCPB)1) and 4-(4-chloro-2-methylphenoxy)butyric acid (MCPB) while liberating 2,4-dichlorophenol (DCP) and 4-chloro-2-methylphenol (MCP) respectively. Some of the isolates were identified by 16S rDNA sequence analysis and shown to belong to the genera Aureobacterium sp. (strain K2-17) and Rhodococcus (Rh. erythropolis K2-12). The other strains isolated clustered into these two groups according to fatty acid analysis. Etherolytic cleavage proceeded under neutral to alkaline conditions with an optimum at around pH 8.5. With Aureobacterium sp. No. K2-17, the degradation rate was zero at a pH of 6 but as much as 60% of the maximum activity was observed at pH 10.5. With Rh. erythropolis K2-12, by contrast, pronounced activity was detected at pH 6.5 while degradation was no longer observed at pH 10.5. The maximum rates of cleavage were about 1 mmol DCPB/h.g dry mass with Aureobacterium sp. No. K2-17 and about 0.6 mmol DCPB/h.g dry mass with Rh. erythropolis K2-12. DCPB and MCPB were utilized to the same extent. Substrate cleavage and product formation (DCP) proceeded at almost equal rates with Aureobacterium sp. No. K2-17 and Rh. erythropolis K2-12, which indicates that this compound was not further metabolized. Only phenoxybutyric acid compounds served as substrates; phenoxyacetic acid and phenoxypropionic acid derivatives were not utilized by these strains.
 ...
PMID:Etherolytic cleavage of 4-(2,4-dichlorophenoxy)butyric acid and 4-(4-chloro-2-methylphenoxy)butyric acid by species of Rhodococcus and Aureobacterium isolated from an alkaline environment. 986 9

Phenoxyalkanoic compounds are used worldwide as herbicides. Cupriavidus necator JMP134(pJP4) catabolizes 2,4-dichlorophenoxyacetate (2,4-D) and 4-chloro-2-methylphenoxyacetate (MCPA), using tfd functions carried on plasmid pJP4. TfdA cleaves the ether bonds of these herbicides to produce 2,4-dichlorophenol (2,4-DCP) and 4-chloro-2-methylphenol (MCP), respectively. These intermediates can be degraded by two chlorophenol hydroxylases encoded by the tfdB(I) and tfdB(II) genes to produce the respective chlorocatechols. We studied the specific contribution of each of the TfdB enzymes to the 2,4-D/MCPA degradation pathway. To accomplish this, the tfdB(I) and tfdB(II) genes were independently inactivated, and growth on each chlorophenoxyacetate and total chlorophenol hydroxylase activity were measured for the mutant strains. The phenotype of these mutants shows that both TfdB enzymes are used for growth on 2,4-D or MCPA but that TfdB(I) contributes to a significantly higher extent than TfdB(II). Both enzymes showed similar specificity profiles, with 2,4-DCP, MCP, and 4-chlorophenol being the best substrates. An accumulation of chlorophenol was found to inhibit chlorophenoxyacetate degradation, and inactivation of the tfdB genes enhanced the toxic effect of 2,4-DCP on C. necator cells. Furthermore, increased chlorophenol production by overexpression of TfdA also had a negative effect on 2,4-D degradation by C. necator JMP134 and by a different host, Burkholderia xenovorans LB400, harboring plasmid pJP4. The results of this work indicate that codification and expression of the two tfdB genes in pJP4 are important to avoid toxic accumulations of chlorophenols during phenoxyacetic acid degradation and that a balance between chlorophenol-producing and chlorophenol-consuming reactions is necessary for growth on these compounds.
 ...
PMID:Chlorophenol hydroxylases encoded by plasmid pJP4 differentially contribute to chlorophenoxyacetic acid degradation. 1659 83

Elliott soil fulvic acid sensitized the phototransformation of mecoprop in aqueous medium. The reaction was selective, leading to the main formation of 4-chloro-2-methylphenol in aerated and in deoxygenated neutral solution. In turn, 4-chloro-2-methylphenol underwent a fulvic acid-mediated phototransformation. A pH decrease from 8 to 2.2 led to an increase of the rate of mecoprop loss by a factor of 10. The roles of hydroxyl radicals, fulvic triplets and singlet oxygen were investigated using the scavenging technique. At pH 6.5 where mecoprop was in the anionic form, triplet excited states and hydroxyl radicals were the main oxidant species contributing to 40 +/- 10% and 20 +/- 5% of the reaction, respectively. At pH 2.2 where mecoprop was protonated, fulvic triplets and hydroxyl radicals contributed to 75 +/- 10% and 16 +/- 5%, respectively. The enhancement of the reaction upon acidification might result from two phenomena tending to the same effect: (i) the capacity of protonated MCP to reach intra-humic microdomains and there interact with reactive species, and (ii) a greater photosensitizing property of FA in acidic medium.
 ...
PMID:Fulvic acid-mediated phototransformation of mecoprop. A pH-dependent reaction. 1958 84