2003
DOI: 10.1021/ja0378660
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Formation of 13C-, 15N-, and 18O-Labeled Guanidinohydantoin from Guanosine Oxidation with Singlet Oxygen. Implications for Structure and Mechanism

Abstract: Guanosine labeled with 15N at N1, amino, and N7 and 13C at either C2 or C8 was oxidized by Rose Bengal photosensitization (singlet oxygen) in buffered aqueous solution. At pH > 7, spiroiminodihydantoin was the major product, while at pH < 7, guanidinohydantoin (Gh) was the principal product. 15N and 13C NMR studies confirmed that Gh was formed as a mixture of slowly equilibrating diastereomers. Experiments conducted in H218O indicated that Gh and Sp each contained one oxygen atom derived from O2 and one from H… Show more

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Cited by 169 publications
(277 citation statements)
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“…Further work is necessary to confirm the R and S designations of the monomer and oligomers. Of note, Gh also exists as a mixture of diastereomers, but these interconvert on a time scale that is too rapid to allow isolation and independent study (53).…”
Section: Discussionmentioning
confidence: 99%
“…Further work is necessary to confirm the R and S designations of the monomer and oligomers. Of note, Gh also exists as a mixture of diastereomers, but these interconvert on a time scale that is too rapid to allow isolation and independent study (53).…”
Section: Discussionmentioning
confidence: 99%
“…19 Both Gh and Sp were formed via a 5-OH-8-oxoGua intermediate. 20 The use of the metalloporphyrin Mn-TMPyP/KHSO 5 leads to an oxidised Gh ox , not Gh, as the main oxidatively generated product of 75 Guanine oxidation, along with Iz and Oxa. 21 Peroxynitrite oxidation was also found to generate an oxidised form of Gh, oxidised Guanidinohydantoin (Gh ox ) in addition to both Gh and Sp.…”
Section: Introductionmentioning
confidence: 99%
“…Oligonucleotides that contain single, site-specifically inserted Gh or Sp lesions can be separated and purified by anion-exchange HPLC methods (21). In aqueous solutions, the Gh diastereomers are easily interconvertible, and it is, therefore, not feasible to study their characteristics individually (22). In contrast, the Sp-S and Sp-R diastereomers are chemically stable and can be purified and studied individually (10,23).…”
mentioning
confidence: 99%