Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In nerve tissue the histochemical nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) reaction is considered a suitable marker for nitric oxide synthase (NOS) activity. We have previously shown that the NOS-specific inhibitor L-nitroarginine (L-NNA) can block NADPH-d staining in intermediolateral (IML) neurons of the rat spinal cord: such a reaction might serve as a control for the presence of a NOS-related catalytic activity, i.e., L-NNA-dependent NO synthesis in these neurons. However, L-NNA inhibition of neuronal NADPH-d is inconsistent and is therefore disputed by others. This prompted us to reinvestigate the reaction conditions to provide a standardized protocol for inhibition experiments. In IML neurons of formaldehyde-fixed spinal cord tissue, inhibition of NADPH-d reaction was tested by preincubation of frozen sections with the flavin-binder diphenylene iodonium chloride (DPI, 10 microM-1 mM) which blocked the NADPH-d reaction in a concentration-dependent way, suggesting an inverse relationship of inhibitor concentration and final reaction product generated. Preincubation with the NOS-specific inhibitor L-NNA in glycine-NaOH buffer (pH 8.5-9.5) but not L-nitroarginine methyl ester (L-NAME) revealed a concentration-dependent blocking effect on neuronal NADPH-d comparable to the effects seen with DPI, suggesting the existence of a L-NNA sensitive NADPH-d activity. Blocking with L-NNA (100 microM-10 mM) was prevented by excess L-arginine (10-100 mM), suggesting competitive binding sites. NADPH-d staining was not inhibited by 7-nitro indazole, another NOS inhibitor. Thus, in formaldehyde-fixed nervous tissue both DPI and L-NNA inhibit the NOS-associated catalytic NADPH-d activity, thereby preventing NADPH-dependent conversion of nitroblue tetrazolium to formazan.
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PMID:L-NNA inhibits the histochemical NADPH-d reaction in rat spinal cord neurons. 764 Oct 70

Uridine (U) insertion/deletion editing of mitochondrial mRNAs in kinetoplastid protozoa is a posttranscriptional process mediated by guide RNAs (gRNAs). The gRNAs direct the precise insertion and deletion of Us by a cleavage-ligation mechanism involving base pairing. We show that a cognate gRNA in cis at the 3' end of a preedited NADH dehydrogenase 7 (ND7) mRNA substrate can direct U insertions at editing site 1 when incubated with a mitochondrial lysate from Leishmania tarentolae. The efficiency of gRNA-dependent U insertion mediated by a cis-acting gRNA is greater on a molar basis than that for a trans-acting gRNA, as expected for a unimolecular gRNA:mRNA interaction. Blocking the 3' end of a cis-acting gRNA lacking a 3' oligo[U] tail has no effect on gRNA-dependent U insertions, nor does providing the gRNA in cis upstream of the mRNA, confirming the previous observation that the terminal 2'- and 3'-hydroxyls of the gRNA are not involved in U insertion activity. These results also establish that the oligo[U] tail is not required for U insertion in vitro. Increasing the extent of base pairing between the 3' end of the gRNA and the 5' end of the mRNA significantly increases in vitro gRNA-dependent U insertion at site 1, presumably by maintaining the mRNA 5' cleavage fragment within the editing complex. We speculate that, in vivo, protein:RNA and/or protein:protein interactions may be responsible for maintaining the mRNA 5' cleavage fragment in close proximity to the mRNA 3' cleavage fragment, and that such interactions may be rate limiting in vitro.
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PMID:In vitro uridine insertion RNA editing mediated by cis-acting guide RNAs. 1033 36