Ribose sugar

Fig. 3-2 Chemical diagram of ATP (adenosine triphosphate). The three functional groups are the base adenosine (upper right), a five-carbon ribose sugar (middle), and three molecules of phosphate (left). Lines at bottom of sugar ring indicate hydroxyl groups.

The DNA double heUx illustrates the contribution of multiple forces to the structure of biomolecules. While each individual DNA strand is held together by covalent bonds, the two strands of the helix are held together exclusively by noncovalent interactions. These noncovalent interactions include hydrogen bonds between nucleotide bases (Watson-Crick base pairing) and van der Waals interactions between the stacked purine and pyrimidine bases. The hehx presents the charged phosphate groups and polar ribose sugars of... 

DNA and RNA are formed of nucleotides. Each nucleotide or nucleoside is composed of a purine or pyrimidine base linked to the 1-position of a ribose sugar in the case of RNA and a 2 -deoxyribose sugar in the case of DNA.155 The 5 position is phosphorylated in the case of a nucleotide, while the nucleoside is not phosphorylated therefore, nucleotides are nucleoside phosphates. Phosphorylation can include one, two, or three phosphate groups. The most familiar example of a phosphorylated nucleotide is phosphorylated adenosine, which occurs as the mono-, di-, and triphosphate (AMP, ADP, and ATP, respectively) and is a principal means of energy storage in biological systems. 

Figure 14-3. Transesterification reaction of the dinucleotide model where the nucleophile-containing ribose sugar is modelled by a tetrahydrofurane structure, whereas the cleaving sugar is further simplified and modelled as a simple primary alcohol (ethanol)...

Ribozymes are a class of metallo-enzymes based on RNA rather than proteins. They have potential in clinical medicine, for example, as potential anti-HIV agents (568, 569) and as possible new tools for the treatment of cancer (570). The active structures of ribozymes contain domains of stacked helices which pack together through tertiary contacts. Divalent metal ions such as Mg(II), Zn(II), and Mn(II) can tune the reactivity and shape the structures of ribozymes (571). Manganese(II) and Mg(II) have similar hexacoordinate ionic radii (0.86 and 0.97 A, respectively) (572) and octahedral geometry ( )Ka of hydrates Ca(II), 12.7 Mg(II), 11.4 Mn(II), 10.7 Zn2+, 9.6) (571). There are several potential oxygen donors on the ribose sugar moiety. 

By combining the quantitative approach [23] to extract cross-correlated relaxation with resolution enhancement methods using restricted coherence transfer in a so-called forward directed TOCSY [27], Richter et al. could determine the ribose sugar conformation for all but two residues in a uniformly 13C,15N labeled 25mer RNA [28] and compare them to 3J(H, H) values determined using a forward-directed HCC-TOCSY-CCH-E.COSY experiment [29]. 

What are the facts of life One of the most striking is that all known living systems involve the same types of polymers, i.e., three varieties of homochiral biopolymers. That is, each variety is composed of unique molecular building blocks having the same three-dimensional handedness. Thus, with rare exceptions, the proteins found in cells are composed exclusively of the 1-enantiomers of 19 optically active amino acids (Fig. 11.1). Similarly, only D-ribose and 2-deoxy-D-ribose sugars are found in the nucleic acid polymers that make up the RNAs and DNAs, which are essential for protein synthesis in the cell and for the transmission of genetic information from one generation to the next. 

Reetz et al. described the solid-phase enzymatic synthesis of oligonucleotides on Kieselguhr-PDMA-resins via T4 RNA ligase. Goncomitantly, they found that RNase A selectively cleaves the last bound nucleotide at the ribose sugar leaving a 3, 5 - diphosphorylated ohgomer on the resin, but application in synthesis has not yet been undertaken [22]. 

The DNA molecule is a double strand of nucleic acids, each consisting of a sequence of nucleosides, which are paired ribose sugar and phosphoric acid, held together in sequences of [—R(X)—P—], where X is one of four bases of thymine, cytosine, adenine, or guanine. Thymine can bond to adenine by two hydrogen bonds, and cytosine can bond to guanine by three hydrogen bonds. The two strands of DNA molecules run... 

C. Formation of deoxyribonudeotides by reduction of the 2 -hydroxyl group of the ribose sugars on the ribonucleoside diphosphates ADP and GDP is catalyzed by ribonucleotide reductase (Figure 10-3). 

Phosphorylases remove the ribose sugars to yield the bases guanine or hypoxan-thine (from adenine or inosine nucleosides). 

PRPP is an "activated pentose" that participates in the synthesis of purines and pyrimidines, and in the salvage of purine bases (see p. 294). Synthesis of PRPP from ATP and ribose 5-phosphate is catalyzed by PRPP synthetase (ribose phosphate pyrophosphokinase, Figure 22.6). This enzyme is activated by inorganic phosphate (Pi) and inhibited by purine nucleotides (end-product inhibition). [Note The sugar moiety of PRPP is ribose, and therefore ribonucleotides are the end products of de novo purine synthesis. When deoxy-ribonucleotides are required for DNA synthesis, the ribose sugar moiety is reduced (see p. 295).]... 

Figure 13-27 illustrates the two major classes of nucleic acids, distinguished from each other by the MbUKt u.zb type of ribose sugar in the nucleotide monomers. Those without an oxygen... 

A nucleic acid is a long polymeric atom on one of the carbon atoms in the ring of the ribose sugar are deoxyrib-... 

Was this your answer All DNA nucleotides lack an oxygen atom on the ribose sugar. Also, the nitrogenous base in a DNA nucleotide maybe adenine, guanine, cytosine, or thymine.The nitrogenous base in a RNA nucleotide may be adenine, guanine, cytosine, or uracil. 

Nucleotide A nucleic acid monomer consisting of three parts a nitrogenous base, a ribose sugar, and an ionic phosphate group. 

Deoxyribonucleic acid A nucleic acid containing a deoxygenated ribose sugar, having a double helical structure, and carrying genetic code in the nucleotide sequence. 

Ribonucleic acid A nucleic acid containing a fully oxygenated ribose sugar. 

Structures of three common ribonucleotides (a) and four common deoxyribonucleotides (b). See Table 23.1 for alternative names and for names of the corresponding bases and nucleosides. The ribonucleotides contain a ribose sugar, whereas the deoxyribonucleotides have a deoxyribose that lacks a hydroxyl group at C-2 of the pentose. In all cases the phosphoryl group is attached... 

All nucleic acids consist of covalently linked nucleotides. Each nucleotide has three characteristic components (1) a purine or pyrimidine base (2) a pentose and (3) a phosphate group. The purine or pyrimidine bases are linked to the C-T carbon of a deoxyribose sugar in DNA or a ribose sugar in RNA. The phosphate groups are linked to the sugar at the C-5 and C-3 positions. The purine bases in both DNA and RNA are always adenine (A) and guanine (G). The pyrimidine bases in DNA are thymine (T) and cyto-... 

Figure 16.1 The structure of adenosine triphosphate (ATP). The lower ring is a ribose sugar, the upper molecule is the base, adenine. Adenosine diphosphate (ADP) differs from ATP by having two phosphate groups attached instead of three.

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