# Tryptophan—tRNA ligase

Last updated
tryptophan-tRNA ligase
Identifiers
EC number 6.1.1.2
CAS number 9023-44-3
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures
Gene Ontology

In enzymology, a tryptophan-tRNA ligase (EC 6.1.1.2) is an enzyme that catalyzes the chemical reaction

The Enzyme Commission number is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze. As a system of enzyme nomenclature, every EC number is associated with a recommended name for the respective enzyme.

Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst, which is not consumed in the catalyzed reaction and can continue to act repeatedly. Because of this, only very small amounts of catalyst are required to alter the reaction rate in principle.

A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei, and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.

ATP + L-tryptophan + tRNATrp ${\displaystyle \rightleftharpoons }$ AMP + diphosphate + L-tryptophyl-tRNATrp

The 3 substrates of this enzyme are ATP, L-tryptophan, and tRNA(Trp), whereas its 3 products are AMP, diphosphate, and L-tryptophyl-tRNATrp.

Adenosine triphosphate (ATP) is a complex organic chemical that provides energy to drive many processes in living cells, e.g. muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all forms of life, ATP is often referred to as the "molecular unit of currency" of intracellular energy transfer. When consumed in metabolic processes, it converts either to adenosine diphosphate (ADP) or to adenosine monophosphate (AMP). Other processes regenerate ATP so that the human body recycles its own body weight equivalent in ATP each day. It is also a precursor to DNA and RNA, and is used as a coenzyme.

Products are the species formed from chemical reactions. During a chemical reaction reactants are transformed into products after passing through a high energy transition state. This process results in the consumption of the reactants. It can be a spontaneous reaction or mediated by catalysts which lower the energy of the transition state, and by solvents which provide the chemical environment necessary for the reaction to take place. When represented in chemical equations products are by convention drawn on the right-hand side, even in the case of reversible reactions. The properties of products such as their energies help determine several characteristics of a chemical reaction such as whether the reaction is exergonic or endergonic. Additionally the properties of a product can make it easier to extract and purify following a chemical reaction, especially if the product has a different state of matter than the reactants. Reactants are molecular materials used to create chemical reactions. The atoms aren't created or destroyed. The materials are reactive and reactants are rearranging during a chemical reaction. Here is an example of reactants: CH4 + O2. A non-example is CO2 + H2O or "energy".

Adenosine monophosphate (AMP), also known as 5'-adenylic acid, is a nucleotide. AMP consists of a phosphate group, the sugar ribose, and the nucleobase adenine; it is an ester of phosphoric acid and the nucleoside adenosine. As a substituent it takes the form of the prefix adenylyl-.

This enzyme belongs to the family of ligases, to be specific those forming carbon-oxygen bonds in aminoacyl-tRNA and related compounds. The systematic name of this enzyme class is L-tryptophan:tRNATrp ligase (AMP-forming). Other names in common use include tryptophanyl-tRNA synthetase, L-tryptophan-tRNATrp ligase (AMP-forming), tryptophanyl-transfer ribonucleate synthetase, tryptophanyl-transfer ribonucleic acid synthetase, tryptophanyl-transfer RNA synthetase, tryptophanyl ribonucleic synthetase, tryptophanyl-transfer ribonucleic synthetase, tryptophanyl-tRNA synthase, tryptophan translase, and TrpRS. This enzyme participates in tryptophan metabolism and aminoacyl-trna biosynthesis.

In biochemistry, a ligase is an enzyme that can catalyze the joining of two large molecules by forming a new chemical bond, usually with accompanying hydrolysis of a small pendant chemical group on one of the larger molecules or the enzyme catalyzing the linking together of two compounds, e.g., enzymes that catalyze joining of C-O, C-S, C-N, etc. In general, a ligase catalyzes the following reaction:

## Structural studies

As of late 2007, 21 structures have been solved for this class of enzymes, with PDB accession codes 1D2R, 1I6K, 1I6L, 1I6M, 1M83, 1MAU, 1MAW, 1MB2, 1O5T, 1R6T, 1R6U, 1ULH, 1YIA, 1YID, 2A4M, 2AKE, 2AZX, 2DR2, 2G36, 2IP1, and 2OV4.

The Protein Data Bank (PDB) is a database for the three-dimensional structural data of large biological molecules, such as proteins and nucleic acids. The data, typically obtained by X-ray crystallography, NMR spectroscopy, or, increasingly, cryo-electron microscopy, and submitted by biologists and biochemists from around the world, are freely accessible on the Internet via the websites of its member organisations. The PDB is overseen by an organization called the Worldwide Protein Data Bank, wwPDB.

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## References

• DAVIE EW, KONINGSBERGER VV, LIPMANN F (1956). "The isolation of a tryptophan-activating enzyme from pancreas". Arch. Biochem. Biophys. 65 (1): 21–38. doi:10.1016/0003-9861(56)90173-4. PMID   13373404.
• Preddie EC (1969). "Tryptophanyl transfer ribonucleic acid synthetase from bovine pancreas. II. The chemically different subunits". J. Biol. Chem. 244 (14): 3958–68. PMID   5805407.
• Wong KK, Meister A, Moldave K (1959). "Enzymic formation of ribonucleic acid-amino acid from synthetic aminoacyladenylate and ribonucleic acid". Biochim. Biophys. Acta. 36: 531–533. doi:10.1016/0006-3002(59)90196-9. PMID   13845797.

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