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Literature summary for 3.1.26.4 extracted from

  • Bastock, J.A.; Webb, M.; Grasby, J.A.
    The pH-dependence of the Escherichia coli RNase HII-catalysed reaction suggests that an active site carboxylate group participates directly in catalysis (2007), J. Mol. Biol., 368, 421-433.
    View publication on PubMed

Cloned(Commentary)

Cloned (Comment) Organism
overexpression of RNase HII in strain Bl21 (DE3) Escherichia coli

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
additional information
-
additional information Michaelis-Menten kinetics with different DNA-RNA hybrids Escherichia coli

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+ activates Escherichia coli

Organism

Organism UniProt Comment Textmining
Escherichia coli
-
-
-

Purification (Commentary)

Purification (Comment) Organism
recombinant RNase HII from strain BL21(DE3) to near homogeneity by a combination of ion exchange and affinity chromatography Escherichia coli

Reaction

Reaction Comment Organism Reaction ID
Endonucleolytic cleavage to a 5'-phosphomonoester possible mechanisms for the RNase HII-catalysed reaction consistent with the pH-dependent behaviour of the enzyme, the active sites of RNase H enzymes contain a cluster of four strictly conserved carboxylate groups, requirement for ionisation of an active site carboxylic acid for metal ion binding or correct positioning of metal ion in the enzyme-substrate complex and a role for a second active site carboxylate in general base catalysis Escherichia coli

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
DNA-RNA hybrid + H2O RNase HII specifically catalyses the hydrolysis of phosphate diester linkages contained within the RNA portion of DNA/RNA hybrids, usage of 5'-fluorescent oligodeoxynucleotide substrates Escherichia coli ?
-
?

Synonyms

Synonyms Comment Organism
ribonuclease H
-
Escherichia coli
RNase HII
-
Escherichia coli

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
additional information
-
additional information the logarithm of the turnover number of the enzyme increases steeply with pH until a pH-independent region is reached close to neutrality Escherichia coli

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
6.5
-
the logarithm of the turnover number of the enzyme increases steeply with pH until a pH-independent region is reached close to neutrality, the pH-dependence of log 1/KM is a sigmoidal curve reaching a maximal value at higher pH, suggesting deprotonation of a residue stabilises substrate binding Escherichia coli

pH Range

pH Minimum pH Maximum Comment Organism
6.5 8
-
Escherichia coli