Ribonucleic acid residues

KhGH A natural, stmctural variant of hGH called 20-K hGH has been reported to occur in the pituitary as well as in the bloodstream (12,13). This variant, which lacks the 15 amino acid residues from Glu-32 to Gln-46, arises from an alternative splicing of the messenger ribonucleic acid (mRNA) (14). This variant shares many but not all of the biological properties of hGH. 

The unique characteristic of each protein is the distinctive sequence of amino acid residues in its polypeptide chain(s). Indeed, it is the amino acid sequence of proteins that is encoded by the nucleotide sequence of DNA. This amino acid sequence, then, is a form of genetic information. By convention, the amino acid sequence is read from the N-terminal end of the polypeptide chain through to the C-terminal end. As an example, every molecule of ribonucle-... 

The position was somewhat clarified by the isolation of 2- and 3-O-phos-phonucleosides from ribonucleic acid hydrolyzates in 92 to 100% yields,134 and also by the demonstration that 5-O-phosphonucleosides are also present in enzymic digests.49, 197 Yet this information gave no indication of the nature of the alkali-labile linkages. Thus, while the majority of the experimental evidence pointed to the phosphoryl residues as being doubly esterified with adjacent nucleosides, two facts remained apparently inexplicable on the basis of this type of structure. First, ready fission by alkalis, and secondly, the absence of 5-phosphates from alkaline hydrolyzates and their presence in enzymic digests. Both these facts have been explained by Brown and Todd in the following way.92... 

The nucleic acids play a central role in the storage and expression of genetic information (see p. 236). They are divided into two major classes deoxyribonucleic acid (DNA) functions solely in information storage, while ribonucleic acids (RNAs) are involved in most steps of gene expression and protein biosynthesis. All nucleic acids are made up from nucleotide components, which in turn consist of a base, a sugar, and a phosphate residue. DNA and RNA differ from one another in the type of the sugar and in one of the bases that they contain. 

Polynucleotides consisting of ribonucleotide components are called ribonucleic acid (RNA), while those consisting of deoxyribonu-cleotide monomers are called deoxyribonucleic acid (DNA see p. 84). To describe the structure of polynucleotides, the abbreviations for the nucleoside components are written from left to right in the 5 - 3 direction. The position of the phosphate residue is also sometimes indicated by a p . In this way, the structure of the RNA segment shown Fig. 2 can be abbreviated as. .pUpG.. or simply as... 

Interferon-a2 concentrated solution is a solution of a protein that is produced according to the information coded by the o2 sub-species of interferon-a gene and that exerts non-specific antiviral activity, at least in homologous cells, through cellular metabolic processes involving synthesis of both ribonucleic acid and protein. Interferon-a2 concentrated solution also exerts antiproliferative activity. Different types of interferon a2, varying in the amino acid residue at position 23, are designated by a letter in lower case. 

The pH-rate profile for the action of the enzyme shows a typical pH maximum, with sharply lower rates at either higher or lower pH than the optimum these facts suggest that both an acidic and a basic group are required for activity (Herries, 1960). The two essential histidine residues could serve as these groups if, in the active site, one were protonated and the other present in its basic form. The simultaneous acid-base catalysis would parallel that of the model system (discussed below) of Swain and J. F. Brown. The essential lysine, which binds phosphate, presumably serves to bind a phosphate residue of the ribonucleic acid. These facts led Mathias and coworkers to propose the mechanism for the action of ribonuclease that is shown in (13) (Findlay et al., 1961). 

Pyrimidine natural products are particularly important (Scheme lb). The nucleic acids contain pyrimidine and purine bases ribonucleic acids (RNA) contain D-ribose and uracil, deoxyribonucleic acids (DNA) contain 2-deoxy-D-ribose and thymine and both types contain phosphate residues,... 

Ribonuclease is an enzyme with 124 amino acids. Its function is to cleave ribonucleic acid (RNA) into small fragments. A solution containing pure protein, with no other ions present except H+ and OH- derived from the protein and water, is said to be isoionic. From this point near pH 9.6 in the graph, the protein can be titrated with acid or base. Of the 124 amino acids, 16 can be protonated by acid and 20 can lose protons to added base. From the shape of the titration curve, it is possible to deduce the approximate pATa for each titratable group.1-2 This information provides insight into the environment of that amino acid in the protein. In ribonuclease, three tyrosine residues have "normal values of pATa(=10) (Table 10-1) and three others have pA a >12. The interpretation is that three tyrosine groups are accessible to OH, and three are buried inside the protein where they cannot be easily titrated. The solid line in the illustration is calculated from pA"a values for all titratable groups. 

Because of their relatively low molecular weight (70 to 90 nucleotide residues), transfer ribonucleic acids are of special interest for 13C NMR investigations [769, 778, 782-784] of nucleic acids. Using a tube of 20 mm o.d., a sample of thermally denatured yeast... 

Figure 7.5 Example of a chimeric oligonucleic acid and its modification. Chimeric RNA-DNA hybrids are used for correction of point mutations in target genes. One strand of this oligonucleic acid is composed of O-methyl-RNA (outline) with an interruption of 5 bases of deoxyribonucleic acid. X and Y are target residues for correction. In the complementary strand, there is a DNA nick, and T residues loop both ends. 3 -exonuclease and FEN-1 may act on the nick, PARP-1 possibly binds to and is activated by the nick, resulting in activation of damage response pathways. In the modified version, the 3 end is replaced by ribonucleic acids. The 5 end is extended, and the flipped back RNA tail is added. Thus, the nick is expected to be resistant to 3 -exonuclease and FEN-1. In addition, PARP-1 may not be activated by such a nick.

Deoxyribonucleic acid is the genetic material such that the information to make all the functional macromolecules of the cell is preserved in DNA (Sinden, 1994). Ribonucleic acids occur in three functionally different classes messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA) (Simons and Grun-berg-Manago, 1997). Messenger RNA serves to carry the information encoded from DNA to the sites of protein synthesis in the cell where this information is translated into a polypeptide sequence. Ribosomal RNA is the component of ribosome which serves as the site of protein synthesis. Transfer RNA (tRNA) serves as a carrier of amino acid residues for protein synthesis. Amino acids are attached as aminoacyl esters to the 3 -termini of the tRNA to form aminoacyl-tRNA, which is the substrate for protein biosynthesis. 

Ribonuclease, the enzyme that hydrolyzes ribonucleic acids (Chap. 7), contains four disulfide bonds that help to stabilize its conformation. In the presence of 6 M guanidine hydrochloride, to weaken hydrogen bonds and hydrophobic interactions, and 1 mM mercaptoethanol, to reduce the disulfide bonds, all enzymatic activity is lost, and there is no sign of residual secondary structure. On removing the guanidine hydrochloride by dialysis or gel filtration, enzymatic activity is restored, the native conformation is regained, and correct disulfide bonds are reformed. 

---