Search results for "Hydro-Lyases"
showing 10 items of 13 documents
Purification of rat liver epoxide hydratase to apparent homogeneity.
1975
Epoxide hydratase (EC 4.2.1.63) is a microsomal enzyme which catalyses the conversion of epoxides to trans-dihydrodiols. Epoxides, produced by the action of microsomal monooxygenases (EC 1.14.1.1) from aromatic and olefinic compounds, are thought to be responsible for many of the harinful effects of polycyclic hydrocarbons and related compounds. Thus epoxide hydratase, together with glutathione 9transferases, (EC 2.5.1.18) may play an important role in the removal of carcinogenic and cytotoxic metabolites (for reviews see [l-3]). It has been reported [4,5] that dihydrodiols formed from some polycyclic hydrocarbons (benz(a)anthracene and benzo(a)pyrene) are reactivated by the microsomal mono…
Properties and amino acid composition of pure epoxide hydratase
1975
1. Introduction Rat liver epoxide hydratase [EC 4.2.1.631 which catalyses the conversion of epoxides to trurans-dihydro- diols has been purified to apparent homogeneity as determined by three independent criteria [l] . The preparation obtained was capable of catalysing the hydration of both styrene oxide and the 4,5- (K- region)epoxide of benzo(a)pyrene [ 11. Epoxides of polycyclic hydrocarbons have been implicated as the agents responsible for the cytotoxic and carcinogenic properties of such compounds (for reviews see [2-41). A detailed knowledge of the properties of epoxide hydratase may, therefore, contribute towards an understanding of the mechanisms of cytotoxicity and carcinogenesis.…
Antibodies against homogeneous epoxide hydratase provide evidence for a single enzyme hydrating styrene oxide and benz(a)pyrene 4,5-oxide
1976
THE microsomal enzyme epoxide hydratase (EC 4.2.1.63) is potentially important in the inactivation of metabolically produced epoxides which may be responsible for the mutagenic and/or carcinogenic properties of polycyclic hydrocarbons (for reviews see refs 1–3). Reports4,5 suggest that the enzyme plays a dual role in (a) producing proximate carcinogens which, after biotransformation to carcinogens by microsomal mono-oxygenase(s) are (b) inactivated by epoxide hydratase. As this enzyme can be induced6–8, activated9–10 and inhibited9–13 it should be useful in studies of the mechanism of chemical carcinogenesis: some inverse correlations have been reported between susceptibility to carcinogene…
Targeted disruption of the peroxisomal thiolase B gene in mouse: a new model to study disorders related to peroxisomal lipid metabolism
2004
The peroxisomal beta-oxidation system consists of four steps catalysed by three enzymes: acyl-CoA oxidase, 3-hydroxyacyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase (multifunctional enzyme) and thiolase. In humans, thiolase activity is encoded by one gene, whereas in rodents, three enzymes encoded by three distinct genes (i.e. thiolase A, thiolase B and SCP2/thiolase) catalyse the thiolase activity. So far, acyl-CoA oxidase- and multifunctional enzyme-deficient patients have been identified and knock-out mice for these genes have been produced. Conversely, no isolated thiolase-deficient patient has been found, and no thiolase (A or B)-deficient mice have been generated. Hence, to better u…
A DNA region ofTorulaspora delbrueckii containing theHIS3 gene: sequence, gene order and evolution
2003
We cloned a genomic DNA fragment of the yeast Torulaspora delbrueckii by complementation of a Saccharomyces cerevisiae his3 mutant strain. DNA sequence analysis revealed that the fragment contained two complete ORFs, which share a high similarity with S. cerevisiae His3p and Mrp51p, respectively. The cloned TdHIS3 gene fully complemented the his3 mutation of S. cerevisiae, confirming that it encodes for the imidazoleglycerol-phosphate dehydrate of T. delbrueckii. Two additional ORFs, with a high homology to S. cerevisiae PET56 and DED1 genes, were mapped upstream and downstream from TdHIS3 and TdMRP51, respectively. This genetic organization is analogous to that previously found in Saccharo…
Molecular characterization of the leucine cluster in Buchnera PSY, primary endosymbiont of the aphid Pemphigus spyrothecae
2002
ABSTRACT Buchnera strains from most aphid subfamilies studied to date have been found to carry the leucine gene cluster ( leuA , - B , - C , and - D ) on a plasmid, an organization unique among bacteria. Here, however, we demonstrate a classical chromosomal location of the cluster in Buchnera sp. strain PSY from the aphid Pemphigus spyrothecae (subfamily Pemphiginae). The genes that flank leuABCD in Buchnera sp. strain PSY appear to be adjacent in the genome of Buchnera sp. strain APS, a strain carrying a leucine plasmid. We propose that the presence of a leucine plasmid predates the diversification of symbiotic Buchnera and that the chromosomal location observed in Buchnera sp. strain PSY …
Prognostic significance of miR-34a in Ewing sarcoma is associated with cyclin D1 and ki-67 expression.
2014
ABSTRACT Background At diagnosis, identification of reliable biological indicators of prognosis to allow stratification of patients according to different risks is an important but still unresolved aspect in the treatment of Ewing sarcoma (EWS) patients. This study aimed to explore the role of miR-34A expression on prognosis of EWS patients. Patients and methods Specimens from 109 patients with non-metastatic EWS treated at the Rizzoli Institute with neoadjuvant chemotherapy (protocols ISG/SSGIII, EW-1, EW-2, EW-REN2, EW-REN3, EW-PILOT) and 17 metastases were studied. Sixty-eight patients (62%) remained disease-free and 41 (38%) relapsed (median follow-up: 67 months, range 9–241 months). Ex…
Transcriptional analysis of the nitrile‐degrading operon from Rhodococcus sp. ACV2 and high level production of recombinant amidase with an Escherich…
1999
Northern blotting analysis with RNA probes derived from amidase and nitrile hydratase genes from Rhodococcus sp. ACV2 revealed that both genes are part of the same operon. RNase protection mapping and sequence analysis indicated that the operon is probably under the control of a sigma 70-like promoter located upstream from the amidase gene. Plasmids were constructed with the cloned genes under tac and lac promoter control. Expression of amdA was demonstrated in Escherichia coli. In another construction, the amdA gene was inserted under the control of the bacteriophage T7 promoter. Large amounts of recombinant amidase (at least 20% of total proteins) in a soluble and active form were obtaine…
Prevention of benzo(a)pyrene-induced mutagenicity by homogeneous epoxide hydratase
1976
Benzo(a)pyrene and benz(a)anthrancene which, in contrast to the K-region epoxides benzo(a)pyrene 4,5-oxide and benz(a)anthracene 5,6-oxide, are not mutagenic to Salmonella typhimurium TA 1537 in the absence of mammalian enzyme preparations, were activated by liver microsomes from C3H mice, which had not received any pretreatment, to mutagens reverting this tester strain to histidine prototrophy. Addition of epoxide hydratase inhibitors greatly increased this mutagenicity and addition of pure epoxide hydratase reduced it by more than 95% down to the range of spontaneous mutations as observed in absence of any added mutagen. This demonstrates that the metabolic pathway responsible for the mut…
Enhanced levels of S-linalool by metabolic engineering of the terpenoid pathway in spike lavender leaves
2013
Transgenic Lavandula latifolia plants overexpressing the linalool synthase (LIS) gene from Clarkia breweri, encoding the LIS enzyme that catalyzes the synthesis of linalool were generated. Most of these plants increased significantly their linalool content as compared to controls, especially in the youngest leaves, where a linalool increase up to a 1000% was observed. The phenotype of increased linalool content observed in young leaves was maintained in those T1 progenies that inherit the LIS transgene, although this phenotype was less evident in the flower essential oil. Cross-pollination of transgenic spike lavender plants allowed the generation of double transgenic plants containing the …