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Ribose 2-0-methyl

Methyl ethers of 2-amino-2-deoxy-D-allose have been prepared in order to be subsequently degraded into methyl ethers of n-ribose. Methylation of methyl 2-acetamido-4,6-0-benzylidene-2-deoxy-o -D-alloside gave the 3-methyl ether, which, in turn, was hydrolyzed to afford methyl 2-acetamido-2-deoxy-3-0-methyl-a-D-allopyranoside. After partial methylation, a dimethyl ether, probably the 3,6, was isolated, whereas exhaustive methylation afforded the 3,4,6-trimethyl ether. An identical trimethyl ether was isolated after methylation of methyl 2-acetamido-3,4,6-tri-0-acetyl-2-deoxy-a-n-alloside. Hydrolysis of the methyl glycosides of both the 3-methyl and the 3,4,6-trimethyl ethers gave crystalline hydrochlorides, and the base of the former ether was characterized by means of its crystalline Schiff base with 2-hydroxynaphthaldehyde. [Pg.202]

Different types of substitution/conversion-editing have been described. The best characterised involves cytidine deamination to uridine in the editing of transcripts for apolipoprotein B, and adenosine deamination to inosine in the editing of the transcripts encoding the glutamate receptor subunits. More than 90 different types of base modifications have been described. Moreover, methylations and substitutions of the ribose and phosphate moieties have also been identified. Recently, the 2 -0-ribose methylation has been the focus of much attention since the discovery that the snoRNA guides the methylation in a frans-acting fashion. [Pg.211]

Kiss-Laszlo, Z., Henry, Y., Bachellerie, et al. (1996) Site-specific ribose methylation of preribosomal RNA A novel function for small nucleolar RNAs. Cell 85 1077. [Pg.722]

Modification of the 2 -hydroxyl moiety on the ribose can also occur in the anticodon loop of tRNA. Although methylation of nucleosides is widespread, 2 -0-ribose methylation is found occasionally in the first position of the anticodon but not the second or third. Because the modification of nucleosides in and adjacent to the anticodon loop of tRNA is commonplace, Satoh et examined the decoding efficiency of tRNA in a cell-free expression system when either the first, second, or third nucleosides in the anticodon (either C-G-A or C-U-C) were methylated at the 2 -hydroxyl. While 2 -0-methylcytosine (Cm) in the first position increased the translational efficiency, methylation of both the second and third nucleoside (both the double modification as well as individual methylations at either position) resulted in dramatic reductions in activity. This study serves as a reminder that although methylation may seem simple and diverse throughout the RNA sequence, we still have much to learn about the functionality and biological importance of these modified nucleosides. [Pg.694]

This is small nucleolar RNA or snoRNA. These RNA species recognize their target sequence by base-pairing and then recruit specialized proteins that perform nucleotide modifications to these RNAs usually 2 O-ribose methylation, base deaminations such as adenine-to-inosine conversions, and the addition of pseudouridines. These modifications are crucial to ribosome biogenesis. [Pg.239]

The jS-D-glucosidase of Mucor racemosus was shown to be biosynthesized when the organism was grown in the presence of such diverse carbon sources as glycerol, lactate, o-xylose, o-ribose, methyl and phenyl a-o-glucopyrano-sides, maltose, and cellobiose. Enzyme biosynthesis was strongly repressed in the presence of hexoses and of adenosine 3, 5 -monophosphate. The role of adenosine 3, 5 -monophosphate in the control of jS-D-glucosidase synthesis in M. racemosus was discussed. [Pg.410]

Ribosomal RNA (rRNA) is methylated mostly at the 2 -0-ribose moiety, particularly in eukaryotes, where this type of methylation accounts for 90% of the total methyl groups of rRNA (see review by Maden27), Methylation occurs precociously during the maturation process and before the rRNA precursor is transported to the cyto-plasm ". It is interesting to note that ribose methylation within nucleic acid has also been considered as a polysaccaride modification because RNA resembles a polymer of phosphorylated ribose with a continuous series of purine and pyrimidine bases attached to the glycosidic groups. [Pg.27]

Z unidentified methylated pyrimidine ribose methylated nucleoside(j mam s U... [Pg.29]

Kuge H, Brownlee GG, Geishon PD et al (1998) Cap ribose methylation of c-mos mRNA stimulates translation and oocyte maturatimi in Xenopus laevis. Nucleic Acids Res 26 3208-3214... [Pg.48]

The pathways for thiamine biosynthesis have been elucidated only partiy. Thiamine pyrophosphate is made universally from the precursors 4-amino-5-hydroxymethyl-2-methylpytimidinepyrophosphate [841-01-0] (47) and 4-methyl-5-(2-hydroxyethyl)thiazolephosphate [3269-79-2] (48), but there appear to be different pathways ia the eadier steps. In bacteria, the early steps of the pyrimidine biosynthesis are same as those of purine nucleotide biosynthesis, 5-Aminoimidazole ribotide [41535-66-4] (AIR) (49) appears to be the sole and last common iatermediate ultimately the elements are suppHed by glycine, formate, and ribose. AIR is rearranged in a complex manner to the pyrimidine by an as-yet undetermined mechanism. In yeasts, the pathway to the pyrimidine is less well understood and maybe different (74—83) (Fig. 9). [Pg.92]

The hydroxyl at C-2 in D-ribose is absent in 2-deoxy-D-ribose. In Chapter 28 we shall see how derivatives of 2-deoxy-D-ribose, called deoxyribontideotides, are the fundamental building blocks of deoxyribonucleic acid (DNA), the material responsible for storing genetic information. L-Rhfflnnose is a compound isolated from a number of plants. Its carbon chain terminates in a methyl rather than a CH2OH group. [Pg.1042]

Angier and Marsico followed the course of alkylation first. The 7-dimethylamino-5-methylmercapto derivative reacted with dimethyl sulfate in an alkaline medium to yield a mixture of the 2- and 3-methyl derivatives. The reaction of the 7-diraethylamino derivative with ethyl iodide in an alkaline medium led to a mixture of all three possible monoethyl derivatives. The position of the alkyl group in all these substances was defined by comparing the UV spectra with derivatives prepared by a straightforward synthesis. After reacting the mercuric salts with tri-0-benzoylribofuranosyl chloride, they demonstrated the ribose residue to be bound in position 2. The same structure was shown to be valid for the derivative prepared by Andrews and Barber. ... [Pg.249]

A more complicated reaction sequence has been used by Ukita and Nagasawa (59) in their synthesis of 2-deoxy D-ribose 5-phosphate (2-deoxy D-erythro-pentose 5-(dihydrogen phosphate)), (29). They phosphorylated a mixture of the anomeric methyl deoxyribofuranosides (24)... [Pg.81]

Of the four possible 5-deoxy-pent-4-enofuranoses, the D-erythro-isomer was of interest as a potential source of derivatives of L-lyxofuranose. For this purpose, a vinyl ether having the D-en/ hro-configuration has been prepared from derivatives of D-ribose. Condensation of D-ribose with acetone in the presence of methanol, cupric sulfate and sulfuric acid at 30°C., as described by Levene and Stiller(30) afforded a sirupy product consisting mainly of methyl 2,3-O-isopropylidene-D-ribofuranose (40). Treatment of a pyridine solution of the sirup with tosyl chloride... [Pg.137]

On the other hand, the fragmentation of pyramine obtained from (2 -l3C)AIRs indicated clearly that C-2, in the ribose part, was the precursor of carbon C-7 of the methyl on C-2 of the pyrimidine ring (Scheme 29). This result was confirmed by an experiment with a sample of AIRs labeled with l4C on C-l, C-2, C-3, on the ribose, and C-5 on the imidazole, with an approximate distribution of 1, 1, 3, 3. This precursor produced pyramine with the methyl group almost as radioactive as C-l or C-2, and much less than C-3 of AIRs. Because of the incorporation of C-5 of imidazole into C-4 of pyramine, and the comparable activities of C-3 and C-5 in the precursor AIRs, the specific activity of pyramine... [Pg.301]

It has been shown already that C-2 of ribose is the precursor of the methyl group, and C-l is eliminated in the biosynthesis. The following observation can be pertinent to the point. Pyrimidine (58) is very unstable and quickly decar-boxylates in aqueous solution at room temperature to give pyramine (Scheme 32).67 Thus, if a C-l -C-2 fragment of the ribose part of AIRs became attached by C-2 to C-2 of a pyrimidine, oxidation of C-l to produce a carboxylic acid function could result in its smooth elimination. [Pg.303]

Posttranslational modification of preformed polynucleotides can generate additional bases such as pseudouridine, in which D-ribose is linked to C-5 of uracil by a carbon-to-carbon bond rather than by a P-N-glycosidic bond. The nucleotide pseudouridylic acid T arises by rearrangement of UMP of a preformed tRNA. Similarly, methylation by S-adenosylmethionine of a UMP of preformed tRNA forms TMP (thymidine monophosphate), which contains ribose rather than de-oxyribose. [Pg.289]

Ci7H20O4S2 o-Ribose diphenyl dithioacetal (RIBPTA10)316 Ci8H30O10 Methyl 3,5-0-isopropylidene-2-0-(methyl 3,5-O-isopropyli-dene-a-D-xylofuranosid-3-yl)-a-D-xylofuranoside (MPXFXF)325 C21H42N5Ou+ I- H20 C2HeO Apramycin hydriodide, monohydrate, ethanolate (APRAMI)326... [Pg.372]


See other pages where Ribose 2-0-methyl is mentioned: [Pg.57]    [Pg.1641]    [Pg.407]    [Pg.15]    [Pg.1099]    [Pg.87]    [Pg.728]    [Pg.707]    [Pg.87]    [Pg.778]    [Pg.778]    [Pg.258]    [Pg.27]    [Pg.29]    [Pg.75]    [Pg.141]    [Pg.122]    [Pg.201]    [Pg.89]    [Pg.90]    [Pg.407]    [Pg.23]    [Pg.14]    [Pg.291]    [Pg.50]    [Pg.356]    [Pg.216]    [Pg.96]    [Pg.166]    [Pg.169]    [Pg.235]    [Pg.178]    [Pg.131]   
See also in sourсe #XX -- [ Pg.265 ]




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