Photoreduction of uridine and reduction of dihydrouridine with sodium borohydride

Cerutti, Peter; Kondo, Yoshikazu; Landis, William R.; Witkop, Bernhard

doi:10.1021/ja01005a039

Cited by 43 publications

(14 citation statements)

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“…As well as the cross-adduct, dihydrouracil is also formed by irradiation of uracil and cysteine [3], and this observation assumes greater importance in the light of the formation of dihydrothymine on irradiation of DNA [5,7]. A knowledge of the mechanism of dihydrouracil formation in the presence of hydrogen donors is also relevant to the mechanistic rationalization of the selective, light-dependent reduction of uridine by sodium borohydride [6,7], and the photochemical reduction of uracil in the presence of 2-propanol or other hydrogen donors reported by Elad [8]. This paper reports our investigation of the uracil-cysteine addition reaction as well as an investigation of the photochemical reduction of uracil in 2propanol.…”

mentioning

confidence: 99%

The Mechanism of Photochemical Addition of Cysteine to Uracil and Formation of Dihydrouracil

Jellinek

Johns

1970

Photochem & Photobiology

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A proposed mechanism for the photochemical addition of L-cysteine to uracil with the concurrent formation of dihydrouracil is shown to proceed through the triplet excited state of uracil which can abstract hydrogen atoms from cysteine to form dihydrouracil. This triplet state is the same one as that leading to photodimerization. The thiyl radicals generated add to ground state uracil molecules. The data permit a re-evaluation of the quantum yield for intersystem crossing of uracil in water which shows dimerization in aqueous solution to have a maximum efficiency of 56 per cent. The formation of the cross-adduct and dihydrouracil may be sensitized but the efficiency of the reaction is related to the ability of the sensitizer to be photoreduced and not to its triplet energy.

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mentioning

confidence: 99%

The Mechanism of Photochemical Addition of Cysteine to Uracil and Formation of Dihydrouracil

Jellinek

Johns

1970

Photochem & Photobiology

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“…Earlier studies of NaBH 4 reduction of DHU reported two different products for reactions carried out under different conditions. The principal product formed using a 1:1 NaBH 4 :DHU stoichiometry for 35 min at 0°C is tetrahydrouridine (THU) (Hanze 1967), a well known inhibitor of cytidine deaminase (Wentworth and Wolfenden 1975) that is used in combination cancer chemotherapy (Li et al 2009), whereas more forcing conditions (2:1 stoichiometry, 2 h, room temperature) afforded the doubly reduced, ringopened product N-(b-D-ribofuranosy1)-N-(g-hydroxypropy1)urea (Cerutti et al 1968). In the work reported here, we carried out DHU reduction using conditions typically used in tRNA labeling experiments (a large molar excess of NaBH 4 , 1 h incubation, 0°C (Wintermeyer and Zachau 1979;Pan et al 2009).…”

Section: Dihydrouridine (Dhu) Reduction and Benzohydrazide Substitutionmentioning

confidence: 99%

Fluorescent labeling of tRNA dihydrouridine residues: Mechanism and distribution

Kaur¹,

Raj²,

Cooperman³

2011

RNA

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Dihydrouridine (DHU) positions within tRNAs have long been used as sites to covalently attach fluorophores, by virtue of their unique chemical reactivity toward reduction by NaBH 4 , their abundance within prokaryotic and eukaryotic tRNAs, and the biochemical functionality of the labeled tRNAs so produced. Interpretation of experiments employing labeled tRNAs can depend on knowing the distribution of dye among the DHU positions present in a labeled tRNA. Here we combine matrixassisted laser desorption/ionization mass spectroscopy (MALDI-MS) analysis of oligonucleotide fragments and thin layer chromatography to resolve and quantify sites of DHU labeling by the fluorophores Cy3, Cy5, and proflavin in Escherichia coli tRNA Phe and E. coli tRNA Arg . The MALDI-MS results led us to re-examine the precise chemistry of the reactions that result in fluorophore introduction into tRNA. We demonstrate that, in contrast to an earlier suggestion that has long been unchallenged in the literature, such introduction proceeds via a substitution reaction on tetrahydrouridine, the product of NaBH 4 reduction of DHU, resulting in formation of substituted tetrahydrocytidines within tRNA.

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“…calc. for C,9H,~N30,,SSi, (720.0): C 48.38, H 6.86, N 5.84; found: C 48.51, H 6.80, N 5.58. 3'-0-(3 - Hydroxy-1 ,I ,3.3 -0-(2-(4-ni~rophen~~l)eihyl.~ulfonyl]udenosine (46). In dry pyridine (3 x 15 ml), 39 (4.03 g, 4.3 mmol) was co-evaporated and dissolved in pyridine (15 ml).…”

Section: 6-ddhydro-z'-0-[2-i4-nitrophenyl)e~hyeu~onyl]-3's-0-(i Imentioning

confidence: 99%

Nucleosides. Part LIX. The 2‐(4‐nitrophenyl)ethylsulfonyl (Npes) Group: A New Type of Protection in Nucleoside Chemistry

Pfister

Schirmeister

Mohr

et al. 1995

Helvetica Chimica Acta

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59-77, are treated directly with 2-(4-nitrophenyl)ethylsulfonyl chloride forming in all cases a mixture of the 2',3'-di-U-and the two possible 2'-and 3'-0-monosulfonates 107-148 which can be separated into the pure components by chromatographic methods. The npes group is more labile towards DBU cleavage than the corresponding base-protecting 2-(4-nitrophenyl)ethyl (npe) and 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) groups allowing selective deblocking which is of great synthetic potential.

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Photoreduction of uridine and reduction of dihydrouridine with sodium borohydride

Cited by 43 publications

References 0 publications

The Mechanism of Photochemical Addition of Cysteine to Uracil and Formation of Dihydrouracil

The Mechanism of Photochemical Addition of Cysteine to Uracil and Formation of Dihydrouracil

Fluorescent labeling of tRNA dihydrouridine residues: Mechanism and distribution

Nucleosides. Part LIX. The 2‐(4‐nitrophenyl)ethylsulfonyl (Npes) Group: A New Type of Protection in Nucleoside Chemistry

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