| Transfer ribonucleic acid guanine transglycosylase isolated from rat liver. | |
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MedLine Citation:
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PMID: 6986171 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Transfer ribonucleic acid (tRNA) guanine transglycosylase (guanine insertion enzyme) was isolated from rat liver and extensively purified. The enzyme catalyzes an exchange of queuine (the base of queuosine, Q) as well as its precursors and guanine for guanine originally located in the first position of the anticodon of "undermodified" tRNATyr, tRNAHis, tRNAAsn, and tRNAAsp from an Escherichia coli mutant or rat ascites hepatoma cells. This is in contrast to the previous observation that E. coli tRNA-guanine transglycosylase catalyzes the exchange of queuine precursors, such as 7-(aminoethyl)-7-deazaguanine and 7-cyano-7-deazaguanine, but not of queuine itself [Okada, N., Noguchi, S. Kasai, H., Shindo-Okada, N., Ohgi, T., Goto, T., & Nishimura, S. (1979) J. Biol. Chem. 254, 3067-3073]. The Km value for queuine of the rat liver enzyme is 9.2 X 10(-7) M, much lower than the values for the bases of queuosine precursors or guanine. Thus, the actual substrate for tRNA-guanine transglycosylase in queuosine biosynthesis in vivo in rat liver may not be 7-(aminomethyl)-7-deazaguanine, which is thought to be an actual substrate guanine, the E. coli system. Queuine or some queuine derivative may be the actual substrate for the tRNA-guanine transglycosylase reaction in the biosynthesis of Q in tRNA of mammalian cells. 6-Thioguanine and 8-azaguanine are also found to be good substrates. |
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Authors:
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N Shindo-Okada; N Okada; T Ohgi; T Goto; S Nishimura |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Biochemistry Volume: 19 ISSN: 0006-2960 ISO Abbreviation: Biochemistry Publication Date: 1980 Jan |
Date Detail:
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Created Date: 1980-04-17 Completed Date: 1980-04-17 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0370623 Medline TA: Biochemistry Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 395-400 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Escherichia coli Guanine / analogs & derivatives, metabolism* Kinetics Liver / enzymology* Liver Neoplasms, Experimental / enzymology Nucleoside Q RNA, Transfer Rats Transferases / metabolism* Tyrosine |
| Chemical | |
Reg. No./Substance:
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55520-40-6/Tyrosine; 57072-36-3/Nucleoside Q; 73-40-5/Guanine; 9014-25-9/RNA, Transfer; EC 2.-/Transferases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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