Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.5.1.3 (dihydrofolate reductase)
 5,819 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of K2PtCl4, cis-Pt(NH3)2Cl2, and trans-Pt(NH3)2Cl2 on the activities of glyceraldehyde-3-phosphate dehydrogenase, glucose-6-phosphate dehydrogenase, dihydrofolate reductase, fructose-1,6-bisphosphate aldolase, catalase, tyrosinase, and peroxidase have been investigated. All of the enzymes which are thought to have essential sulfhydryl groups (glyceraldehyde-3-phosphate dehydrogenase, aldolase, and glucose-6-phosphate dehydrogenase) were significantly inhibited by K2PtCl4. The other four enzymes studied are not known to have essential sulfhydryl groups, and were not significantly affected by the Pt compounds under the conditions employed. Glyceraldehyde-3-phosphate dehydrogenase was the only enzyme inhibited by all three Pt compounds tested, with K2PtCl4 being the most effective and cis-Pt(NH3)2Cl2 the least effective inhibitor. Semilogarithmic plots of residual activity versus inhibition time indicated that the inhibition reactions were not simple first-order processes, except for the inhibition of glucose-6-phosphate dehydrogenase by K2PtCl4 which appeared to be first-order with respect to enzyme concentration.
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PMID:The effects of platinum complexes on seven enzymes. 11 85

An expression plasmid containing both human thyroid peroxidase and mouse dihydrofolate reductase cDNAs was transfected into chinese hamster ovary cells. The stably transformed cells constitutively expressed immunoreactive thyroid peroxidase on the cell surface. These cells were further used to establish a subline producing a large amount of thyroid peroxidase by selecting clones resistant to methotrexate. The molecular weight of the expressed thyroid peroxidase was the same as purified human thyroid peroxidase. This expressed protein had peroxidase activity when determined by guaiacol oxidation. Furthermore, the expressed thyroid peroxidase was immunoreactive to sera of patients with autoimmune thyroid disease in which autoantibodies to thyroid peroxidase appeared.
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PMID:Stable high level expression of human thyroid peroxidase in cultured Chinese hamster ovary cells. 259 Feb 1

In a retrospective study the expression of the resistance proteins P-170 glycoprotein (P-170), glutathione S-transferase pi (GST-pi), thymidylate-synthase (TS), dihydrofolate reductase (DHFR) and metallothionein (MT) was investigated in 111 patients with newly diagnosed acute lymphoblastic leukemia (ALL) using the streptavidin-biotin-peroxidase complex method. The expression of the resistance proteins was found in following frequency: P-170 in 39 (35%), GST-pi in 54 (49%), TS in 46 (42%), DHFR in 21 (20%) and MT in 30 (33%) cases of the investigated patients. Patients with overexpression of P-170 or GST-pi had a significant lower probability of remaining in continuous first remission (P < 0.05 for P-170 and P < 0.01 for GST-pi). The expression of TS and DHFR had no prognostic significance on the probability of first remission. Patients with MT-overexpression showed only a tendency for a lower probability of continuous first remission. Coexpression of P-170 and GST-pi was observed in leukemias of 22 patients (21%) and 38 patients (37%) showed no evidence for the expression of both markers. Combining P-170 and GST-pi improved the prognostic value. The expression of the resistance proteins was independent of age, sex, FAB-type, immunological subtype and of the initial peripheral blast cell count. The multivariate analysis indicated that only the expression of P-170 was an independent unfavorable prognostic factor for children with initial ALL. The reason for this was an minor correlation of P-170 and GST-pi (P = 0.01).
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PMID:[Expression and clinical significance of resistance proteins in initial acute lymphatic leukemia (ALL) in childhood]. 756 59

The "dihydrofolate reductase (DHFR) handle" [Iwakura, M. et al. (1992) J. Biochem. 111, 37-45; Iwakura, M. & Tanaka, T. (1992) J. Biochem. 111, 638-642] fused with a pentapeptide, leucine enkephalin (LEK), has been applied in immunoassays for LEK and for the preparation of anti-LEK monoclonal antibody. DHFR fused with LEK (DHFR-LEK) was first utilized as an immobilized antigen in an enzyme-linked immunosorbent assay for LEK. By using a commercially available anti-LEK and peroxidase-linked anti-IgG, LEK could be quantified in the range between 0.1 ng/ml and 10 micrograms/ml. By using a commercially available anti-LEK and the DHFR-LEK as an enzyme-labeled antigen, LEK was quantified in the range between 0.1 ng/ml and 1 microgram/ml by monitoring the recovery of the DHFR activity from the immuno-precipitates. By using the DHFR-LEK as an immunogen, three mouse monoclonal antibodies against LEK, but not DHFR, were isolated. All three monoclonal antibodies were of IgG1 kappa type. The large-scale preparation of two of these monoclonal antibodies, designated as anti-LEK-36 and anti-LEK-74, was carried out and their recognition specificities were studied by competitive binding assays. The IC50 values of LEK for the anti-LEK-36 and anti-LEK-74 were 3.74 x 10(-6) and 4.66 x 10(-6) M, respectively. The competitive binding assays showed that recognition specificities of the two monoclonal antibodies were high and restricted to LEK and leucine-enkephalin (sulfated form). These results strongly suggest that the DHFR handle is useful in several immunological applications.
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PMID:Immunological application of the dihydrofolate reductase handle carrying a small peptide, leucine enkephalin. 813 47

Polycyclic aromatic hydrocarbons (PAH) are widespread environmental contaminants, and some are potent carcinogens in rodents. Carcinogenic PAH are activated in cells to metabolites that react with DNA to form stable covalent DNA adducts. It has been proposed [Cavalieri, E. L. & Roger, E. G. (1995) Xenobiotica 25, 677-688] that unstable DNA adducts are also formed and that apurinic sites in the DNA resulting from unstable PAH adducts play a key role in the initiation of cancer. The potent carcinogen dibenzo[a,l]pyrene (DB[a, l]P) is activated in cells to (+)-syn- and (-)-anti-DB[a,l]P-11, 12-diol-13,14-epoxide (DB[a,l]PDE), which have been shown to form stable adducts with DNA. To evaluate the importance of unstable PAH adducts, we compared stable adduct formation to apurinic site formation. Stable DB[a,l]PDE adducts were determined by 33P-postlabeling and HPLC. To measure apurinic sites they were converted to strand breaks, and these were monitored by examining the integrity of a particular restriction fragment of the dihydrofolate reductase gene. The method easily detected apurinic sites resulting from methylation by treatment of cells or DNA with dimethyl sulfate or from reaction of DNA with DB[a,l]P in the presence of horseradish peroxidase. We estimate the method could detect 0.1 apurinic site in the 14-kb fragment examined. However, apurinic sites were below our limit of detection in DNA treated directly with (+)-syn- or (-)-anti-DB[a,l]PDE or in DNA from Chinese hamster ovary B11 cells so treated, although in these samples the frequency of stable adducts ranged from 3 to 10 per 14 kb. We also treated the human mammary carcinoma cell line MCF-7 with DB[a,l]P and again could not detect significant amounts of unstable adducts. These results indicate that the proportion of stable adducts formed by DB[a,l]P activated in cells and its diol epoxides is greater than 99% and suggest a predominant role for stable DNA adducts in the carcinogenic activity of DB[a,l]P.
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PMID:Formation of stable adducts and absence of depurinating DNA adducts in cells and DNA treated with the potent carcinogen dibenzo[a,l]pyrene or its diol epoxides. 939 Oct 62

We have constructed a retroviral bicistronic vector, MFG/GID, that transduces the expression of both the A3 isoform of the rat glutathione S-transferase (GST A3), and the tyr-22 variant of the human dihydrofolate reductase (DHFR(L22Y)). Transduction of murine 3T3 fibroblasts with this vector increased their in vitro resistance to chlorambucil (1.8-fold) and trimetrexate (TMTX) (748-fold). TMTX selection of a mixed population of 20% GID-transduced NIH 3T3 cells and 80% control cells resulted in a marked increase in the GST peroxidase activity associated with the GST A3 isoform (17.7-fold). MFG/GID-transduced primary clonogenic murine hematopoietic progenitor cells were likewise more resistant to TMTX and chlorambucil than control beta-gal-transduced cells. Selecting GID-transduced hematopoietic cells with a combination of TMTX and a nucleoside transport inhibitor resulted in a marked increase in resistance upon re-exposure to TMTX (99% survival). Similarly, GID-transduced hematopoietic cells selected with TMTX were more resistant to chlorambucil, with 40% survival at a drug concentration that killed practically all control cells. These results suggest that antifolate-mediated selection of MFG/GID-transduced hematopoietic cells could be used as a mean to enrich the population of transduced cells prior to or following transplantation, thus potentially conferring in vivo chemoprotection to nitrogen mustards and antifolates.
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PMID:Increased resistance to nitrogen mustards and antifolates following in vitro selection of murine fibroblasts and primary hematopoietic cells transduced with a bicistronic retroviral vector expressing the rat glutathione S-transferase A3 and a mutant dihydrofolate reductase. 1287 45

Isoniazid is a key drug used in the treatment of tuberculosis. Isoniazid is a pro-drug, which, after activation by the katG-encoded catalase peroxidase, reacts nonenzymatically with NAD(+) and NADP(+) to generate several isonicotinoyl adducts of these pyridine nucleotides. One of these, the acyclic 4S isomer of isoniazid-NAD, targets the inhA-encoded enoyl-ACP reductase, an enzyme essential for mycolic acid biosynthesis in Mycobacterium tuberculosis. Here we show that the acyclic 4R isomer of isoniazid-NADP inhibits the M. tuberculosis dihydrofolate reductase (DHFR), an enzyme essential for nucleic acid synthesis. This biologically relevant form of the isoniazid adduct is a subnanomolar bisubstrate inhibitor of M. tuberculosis DHFR. Expression of M. tuberculosis DHFR in Mycobacterium smegmatis mc(2)155 protects cells against growth inhibition by isoniazid by sequestering the drug. Thus, M. tuberculosis DHFR is the first new target for isoniazid identified in the last decade.
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PMID:Mycobacterium tuberculosis dihydrofolate reductase is a target for isoniazid. 1664 61