TRNA Transfer ribonucleic acid

When the cell requires instructions for protein production, part of the code on DNA, starting at an initiator and ending at a stop codon, is converted into a more mobile form by transferring the DNA code into a matching RNA code on a messenger ribonucleic acid (mRNA), a process known as transcription. The decoding, or translation, of mRNA then takes place by special transfer ribonucleic acids (tRNA), which recognize individual codons as amino acids. The sequence of amino acids is assembled into a protein (see Proteins section). In summary, the codes on DNA... 

Selenocysteine was identified in 1976 (57) in a protein produced by Clostridium stricklandii, and it is thought to be the form in which selenium is incorporated, stoichiometricaHy, into proteins. Studies with rats show that over 80% of the dietary selenium given them is incorporated into proteins, thus selenocysteine takes on metaboHc importance. Selenoproteins having known enzymatic activities contain selenocysteine at the active sites. Two other forms of metabohc selenium are recognized methylated selenium compounds are synthesized for excretion, and selenium is incorporated into some transfer ribonucleic acids (tRNAs) in cultured cells (58). Some of the more important seleno-compounds are Hsted in Table 4. Examples of simple ring compounds are shown in Eigure 4. 

Ribosomal synthesis of peptides proceeds through translation of messenger ribonucleic acid (mRNA) and utilizes the 20 primary L-a-amino acids. These amino acids are incorporated with the use of specific transfer ribonucleic acid (tRNA) codons. The 20 primary a-amino acids, with the exception of glycine that is achiral, are characterized by an L-configuration at the a-position (Figure 1). In general, most proteins are found to be composed of these 20 L-a-amino acids, as such they are referred to as protein amino acids. 

Trans stereochemistry, 41, 106 Transesterification, 85, 90 Transfer ribonucleic acid (tRNA), 37 Transition metal catalysts, 110 Triacontane, 18 Triblock copolymers, 102 Trimec, 262 Tripeptides, 28-30 acidic, 30 Tryptophan, 29 Tyrosine, 29 Tyvek, 170,170... 

Approximately 1000 proteins comprise the mitochondrion the majority are encoded on genes located on nuclear DNA. In fact, as seen in Figure 8-5, the mtDNA encodes only 13 proteins. These mtDNA-encoded proteins are the seven subunits (ND1,2,3,4,4L, 5, and 6) of the NADH-dehydrogenase (RC I) one subunit (cytochrome b) of RC III three subunits (CO I, II, and III) of cytochrome c oxidase (RC IV) and two subunits (A6 and A8) of the ATP synthase (RC V).A11 of these proteins are components of the ETC or the ATP synthase involved in OXPHOS. In addition to these 13 proteincoding genes, the mtDNA encodes 22 mitochondrial transfer ribonucleic acids (tRNAs) and two ribosomal RNA (rRNA) molecules (the large 16S rRNA and the small 12S rRNA). 

Compounds 80, 81 and 82 have been used to assign correctly the 13C-NMR spectra of the covalent adducts which result from nucleophilic attack of bisulphite anion on them66. Previously, uracil labelled with 13C at C(4) has been applied67 to study its incorporation into transfer ribonucleic acid (tRNA) by taking the 13C NMR spectra of 13C-enriched tRNA. The fluidity of the fatty acids within biological membranes has been investigated68 by feeding 13C-labelled acetate. 

Many eucaryotic phenylalanine transfer ribonucleic acids (tRNA ) contain fluorescent components at the position adjacent to the 3 -end of an anticodon. A few related hypermodified nucleosides 1 have been isolated, their structure has been elucidated, and their chemical synthesis been performed. 

The synthesis of a protein requires the mRNA as a template containing the full sequence of codons, including the codon to terminate synthesis. The ribosomes, which orchestrate protein synthesis, read the mRNA in the 5 —>3 direction. (The 5 end has a phosphate group on the 5 -carbon atom of a ribose moiety whereas the 3 end has a phospate group on the 3 -carbon atom of ribose). Protein biosynthesis requires a transfer ribonucleic acid (tRNA) to convey an amino acid to the growing peptide chain. tRNAs are specific for each codon and contain 60-95 nucleotides, a few of which have unusual structures. The 3 end of the tRNA has the sequence... 

The second and third classes of selenoproteins form in a similar manner selenomethionine bound to the transfer ribonucleic acid (tRNA) for methionine competes with methionine bound to the tRNA for... 

The P. falciparum mitochondrion contains 30-100 copies of the genome and encodes only three proteins (cytochrome b and subunits I and III of cytochrome oxidase) and ribosomal ribonucleic acid (rRNA). The rRNA genes are fragmented and scrambled it does not encode any transfer ribonucleic acid (tRNA), ribosomal proteins or ATPase subunits. As such, the Plasmodium mitochondrion denotes an endpoint in the slimming down process whereby the ancient progenitor of all mitochondrial genomes began the slow march to near total dependence on host nuclei (Williamson, 1998). 

The mRNA leaves the nucleus and attaches itself to ribosomal ribonucleic acid (rRNA) in the cytoplasm of the cell. Without going into precise detail, rRNA reads the base-sequence code of mRNA and a third type of RNA, transfer ribonucleic acid (tRNA) brings the correct amino acid to the forming protein. This process is known as translation. Each amino acid is coded for by a sequence of three bases, known as a triplet code. For example, ACA codes for the amino acid cysteine. As amino acids are added in sequence a protein is built up. 

Until recently 1 3C nmr studies of nucleic acids have not received the same attention as those of nucleosides and nucleotides. Poly-uridylic acid (poly U), polyadenylic acid (Poly ), and unfractionated baker s yeast transfer ribonucleic acid (tRNA) have been investigated by 13C nmr techniques (Table 11 Mantsch and Smith, 1972 Komoroski and Allerhand, 1972, 1974). Assignments for uridine monophosphates were based on changes in phosphorus-carbon splittings and on changes in the chemical shift of approximately 2-5 ppm on the phosphorylated carbon, which was caused by the deshielding effect of the phosphate group (Mantsch and Smith,... 

Met-OH and H-Met-Met-Met-OH [32]. In the following decades, aliphatic amino acid esters have been applied in a multitude of studies on enzymatic syntheses of peptides. In the living cell aniino acids esterified to the 2 - or the 3 -hydroxyl group of the terminal adenosine in an aminoacyl transfer ribonucleic acid (tRNA) are the activated intermediates in protein synthesis by ribosomes. 

In the late seventies, Daniel Wayne Armstrong was working as a graduate student in the Janos Fendler s group at Texas A M University (College Station, Texas). His work was related to synthesis and chemical and biochemical reactions in micellar media. To measure the micellar partition coefficient of transfer ribonucleic acids (tRNA), he used the GPC method described by Merries, Bishop and Richards [12]. He got the partition coefficients of the tRNA solutes he was looking for. He readily noticed the separation capability of the method and immediately announced this fact in his very first article on the topic The relative low cost, the ease of operation and shortness oftime for a complete run merit, we believe, the development of this technique to its full potential [13]. 

Ribosyluracil (pseudouridine) is one of the family of unusual nucleosides contained in transfer ribonucleic acid (tRNA), and its determination in urine... 

This approach created problems, though one of the founders of force fields, Michael Levitt, recalls that a model of a Transfer Ribonucleic Acid (tRNA) fragment constructed by him with 2000 atoms weighted more than 50 kg. 

Besides BSA, a single, broad peak was observed also for lysozyme, transfer ribonucleic acid (tRNA), and chondroitin sulfate [32,33]. It was concluded that an ordered structure was formed in these solutions at low salt conditions. For... 

In like manner, ribosomal ribonucleic acid (rRNA) and transfer ribonucleic acid (tRNA) are synthesized from their specific genes through the action of DNA-dependent RNA polymerase. And as in the case of mRNA, each of the precursor forms of these nucleotides are also processed until they reach their final forms. The rRNAs and a large variety of ribosomal proteins are assembled to form the ribosome. Ribosomes, the supramolecular structures in which protein synthesis takes place and which functionally resemble multienzyme complexes, are elaborate structures. They are attached, by a binding site on the smaller subribosomal particle, to the endoplasmic reticulum. The tRNAs that are synthesized finally become charged with specific amino acids. 

It might seem possible that defects in protein synthesis could occur as a result of a defective gene that encodes a specific messenger ribonucleic acid (mRNA), ribosomal ribonucleic acid (rRNA), or transfer ribonucleic acid (tRNA). Flowever, upon reflection, it can be seen that the genes for rRNA and tRNA cannot be defective, since rRNA and tRNA are common to all protein synthesis. A significant defect in the... 

This chapter describes the application of P-NMR spectroscopy to the study of the conformation of transfer ribonucleic acids (tRNAs). The P-NMR spectrum of pure acceptor tRNA species has been shown to contain considerable fine structure (Figs. 1 and 2). High-resolution ip-NMR spectra by Gueron and Shulman (1975) and later by Salemink et al. (1979) and Gorenstein and Luxon (1979) revealed 16 individual phosphate resonances spread over 7 ppm that were not observed in earlier P tRNA spectra (Gueron, 1971 Weiner et al., 1974 Gorenstein and Kar, 1975). 

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