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Literature summary extracted from

  • Airas, R.K.
    Kinetic analysis of the isoleucyl-tRNA synthetase mechanism the next reaction cycle can start before the previous one ends (2018), FEBS open bio, 8, 244-255 .
    View publication on PubMedView publication on EuropePMC

Inhibitors

EC Number Inhibitors Comment Organism Structure
6.1.1.5 chloride 100 mM KCl causes 50% inhibition if the ionic strength is kept constant with potassium acetate. The KappM (tRNA) value is increased from 570 nm to 1370 nM when the KCl concentration is increased from 0 to 200 mM. Potassium acetate inhibits weakly, but K2SO4 inhibits stronger than KCl Escherichia coli
6.1.1.5 K+ potassium acetate inhibits weakly, but K2SO4 inhibits stronger than KCl. KCl and potassium acetate inhibit above 50 mM concentrations when high enough K+ concentration for full activity is reached Escherichia coli

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
6.1.1.5 additional information
-
additional information kinetic analysis, rapid equilibrium determinations, steady-state kinetics. The analysis strongly suggests an additional activation step, formation of a new isoleucyl-AMP before the isoleucyl-tRNA is freed from the enzyme. The removal of Ile-tRNA is possible without the formation of Ile-AMP if both isoleucine and ATP are bound to the E-Ile-tRNA complex, but this route covers only 11% of the total formation of Ile-tRNA. In addition to the Mg2+ in MgATP or Mg-diphosphate, only two tRNA-bound Mg2+ are required to explain the magnesium dependence in the best-fit mechanism. The first Mg2+ might be present in all steps before the second activation and is obligatory in the first reorganizing step and transfer step. The second Mg2+ is present only at the transfer step, whereas elsewhere it prevents the reaction, including the activation reaction Escherichia coli

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
6.1.1.5 Mg2+ required. In addition to the Mg2+ in MgATP or Mg-diphosphate, only two tRNA-bound Mg2+ are required to explain the magnesium dependence in the best-fit mechanism. The first Mg2+ might be present in all steps before the second activation and is obligatory in the first reorganizing step and transfer step. The second Mg2+ is present only at the transfer step, whereas elsewhere it prevents the reaction, including the activation reaction Escherichia coli
6.1.1.5 additional information polyamines can replace part of the Mg2+ ions in the aminoacyl-tRNA synthetase reactions, spermidine can replace Mg2+ (KME3) and Mg2+ (KME42), which are involved in the forward and backward transfer reaction, while the competition with Mg2+ (KMR) is much weaker, kinetics, overview Escherichia coli

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
6.1.1.5 ATP + L-isoleucine + tRNAIle Escherichia coli
-
AMP + diphosphate + L-isoleucyl-tRNAIle
-
?

Organism

EC Number Organism UniProt Comment Textmining
6.1.1.5 Escherichia coli P00956
-
-

Reaction

EC Number Reaction Comment Organism Reaction ID
6.1.1.5 ATP + L-isoleucine + tRNAIle = AMP + diphosphate + L-isoleucyl-tRNAIle catalytic and kinetic mechanism analysis, reaction cycle, overview Escherichia coli

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
6.1.1.5 ATP + L-isoleucine + tRNAIle
-
Escherichia coli AMP + diphosphate + L-isoleucyl-tRNAIle
-
?

Synonyms

EC Number Synonyms Comment Organism
6.1.1.5 IleRS
-
Escherichia coli
6.1.1.5 Isoleucyl-tRNA synthetase
-
Escherichia coli

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
6.1.1.5 30
-
assay at Escherichia coli

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
6.1.1.5 7.4
-
assay at Escherichia coli

Cofactor

EC Number Cofactor Comment Organism Structure
6.1.1.5 ATP
-
Escherichia coli

General Information

EC Number General Information Comment Organism
6.1.1.5 additional information the simultaneous presence of Ile-tRNA and Ile-AMP can cause additional possibilities to proofreading mechanisms of the enzyme, existence of an additional activation step, formation of a new isoleucyl-AMP before the isoleucyl-tRNA is freed from the enzyme. The removal of Ile-tRNA is possible without the formation of Ile-AMP if both isoleucine and ATP are bound to the E-Ile-tRNA complex, but this route covers only 11% of the total formation of Ile-tRNA Escherichia coli