A wobble base pair is a pairing between two nucleotides in RNA molecules that does not follow Watson-Crick base pair rules. The four main wobble base pairs are guanine-uracil (G-U), hypoxanthine-uracil (I-U), hypoxanthine-adenine (I-A), and hypoxanthine-cytosine (I-C). In order to maintain consistency of nucleic acid nomenclature, "I" is used for hypoxanthine because hypoxanthine is the nucleobase of inosine; nomenclature otherwise follows the names of nucleobases and their corresponding nucleosides. The thermodynamic stability of a wobble base pair is comparable to that of a Watson-Crick base pair. Wobble base pairs are fundamental in RNA secondary structure and are critical for the proper translation of the genetic code.
An aminoacyl-tRNA synthetase, also called tRNA-ligase, is an enzyme that attaches the appropriate amino acid onto its corresponding tRNA. It does so by catalyzing the transesterification of a specific cognate amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA. In humans, the 20 different types of aa-tRNA are made by the 20 different aminoacyl-tRNA synthetases, one for each amino acid of the genetic code.
The peptidyl transferase is an aminoacyltransferase as well as the primary enzymatic function of the ribosome, which forms peptide bonds between adjacent amino acids using tRNAs during the translation process of protein biosynthesis. The substrates for the peptidyl transferase reaction are two tRNA molecules, one bearing the growing peptide chain and the other bearing the amino acid that will be added to the chain. The peptidyl chain and the amino acids are attached to their respective tRNAs via ester bonds to the O atom at the CCA-3' ends of these tRNAs. Peptidyl transferase is an enzyme that catalyzes the addition of an amino acid residue in order to grow the polypeptide chain in protein synthesis. It is located in the large ribosomal subunit, where it catalyzes the peptide bond formation. It is composed entirely of RNA. The alignment between the CCA ends of the ribosome-bound peptidyl tRNA and aminoacyl tRNA in the peptidyl transferase center contribute to its ability to catalyze these reactions. This reaction occurs via nucleophilic displacement. The amino group of the aminoacyl tRNA attacks the terminal carboxyl group of the peptidyl tRNA. Peptidyl transferase activity is carried out by the ribosome. Peptidyl transferase activity is not mediated by any ribosomal proteins but by ribosomal RNA (rRNA), a ribozyme. Ribozymes are the only enzymes which are not made up of proteins, but ribonucleotides. All other enzymes are made up of proteins. This RNA relic is the most significant piece of evidence supporting the RNA World hypothesis.
Activation, in chemistry and biology, is the process whereby something is prepared or excited for a subsequent reaction.
Aminoacyl-tRNA is tRNA to which its cognate amino acid is chemically bonded (charged). The aa-tRNA, along with particular elongation factors, deliver the amino acid to the ribosome for incorporation into the polypeptide chain that is being produced during translation.
In enzymology, an isoleucine—tRNA ligase is an enzyme that catalyzes the chemical reaction
In enzymology, a leucine—tRNA ligase is an enzyme that catalyzes the chemical reaction
In enzymology, a lysine—tRNA ligase is an enzyme that catalyzes the chemical reaction
In enzymology, a methionine—tRNA ligase is an enzyme that catalyzes the chemical reaction
In enzymology, a phenylalanine—tRNA ligase is an enzyme that catalyzes the chemical reaction
In enzymology, a tryptophan-tRNA ligase is an enzyme that catalyzes the chemical reaction
Tyrosine—tRNA ligase, also known as tyrosyl-tRNA synthetase is an enzyme that is encoded by the gene YARS. Tyrosine—tRNA ligase catalyzes the chemical reaction
In enzymology, a valine—tRNA ligase is an enzyme that catalyzes the chemical reaction
In enzymology, an alanylphosphatidylglycerol synthase is an enzyme that catalyzes the chemical reaction
Bifunctional aminoacyl-tRNA synthetase is an enzyme that in humans is encoded by the EPRS gene.
Glutaminyl-tRNA synthetase is an enzyme that in humans is encoded by the QARS gene.
Probable histidyl-tRNA synthetase, mitochondrial is an enzyme that in humans is encoded by the HARS2 gene.
Amino acid activation refers to the attachment of an amino acid to its respective transfer RNA (tRNA). The reaction occurs in the cell cytosol and consists of two steps: first, the enzyme aminoacyl tRNA synthetase catalyzes the binding of adenosine triphosphate (ATP) to a corresponding amino acid, forming a reactive aminoacyl adenylate intermediate and releasing inorganic pyrophosphate (PPi). Subsequently, aminoacyl tRNA synthetase binds the AMP-amino acid to a tRNA molecule, releasing AMP and attaching the amino acid to the tRNA. The resulting aminoacyl-tRNA is said to be charged.
Aminoacyl-tRNA synthetases, class II is a family of proteins. These proteins catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction. These proteins differ widely in size and oligomeric state, and have a limited sequence homology.
The aminoacyl-tRNA synthetases catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction. These proteins differ widely in size and oligomeric state, and have limited sequence homology. The 20 aminoacyl-tRNA synthetases are divided into two classes, I and II. Class I aminoacyl-tRNA synthetases contain a characteristic Rossmann fold catalytic domain and are mostly monomeric. Class II aminoacyl-tRNA synthetases share an anti-parallel beta-sheet fold flanked by alpha-helices, and are mostly dimeric or multimeric, containing at least three conserved regions. However, tRNA binding involves an alpha-helical structure that is conserved between class I and class II synthetases. In reactions catalysed by the class I aminoacyl-tRNA synthetases, the aminoacyl group is coupled to the 2'-hydroxyl of the tRNA, while, in class II reactions, the 3'-hydroxyl site is preferred. The synthetases specific for arginine, cysteine, glutamic acid, glutamine, isoleucine, leucine, methionine, tyrosine, tryptophan and valine belong to class I synthetases; these synthetases are further divided into three subclasses, a, b and c, according to sequence homology. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, lysine, phenylalanine, proline, serine, and threonine belong to class-II synthetases.
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