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Literature summary for 3.1.26.4 extracted from

  • Hirano, N.; Haruki, M.; Morikawa, M.; Kanaya, S.
    Enhancement of the enzymatic activity of ribonuclease HI from Thermus thermophilus HB8 with a suppressor mutation method (2000), Biochemistry, 39, 13285-13294.
    View publication on PubMed

Cloned(Commentary)

Cloned (Comment) Organism
gene rnhA, overexpression in Escherichia coli MIC3001 of wild-type and mutant enzymes, complementation of enzyme-dependent temperature-sensitive growth phenotype of the Escherichia coli host strain by expression of the wild-type enzyme, but only marginally by the mutant D134H Thermus thermophilus

Protein Variants

Protein Variants Comment Organism
A12S random mutagenesis, roughly cumulative effect on enzyme activity, increased kcat/Km value compared to the wild-type enzyme Thermus thermophilus
A12S/K75M/A77P site-directed mutagenesis, 40fold increased kcat/Km value compared to the wild-type enzyme, thermal stability similar to the wild-type enzyme Thermus thermophilus
A77P random mutagenesis, roughly cumulative effect on enzyme activity, increased kcat/Km value compared to the wild-type enzyme Thermus thermophilus
D134H site-directed mutagenesis, active site mutant, highly reduced catalytic activity Thermus thermophilus
D134N site-directed mutagenesis, active site mutant, similar to the wild-type enzyme Thermus thermophilus
K75M random mutagenesis, roughly cumulative effect on enzyme activity, increased kcat/Km value compared to the wild-type enzyme Thermus thermophilus
additional information isolation of a mutant enzyme with enhanced activity at moderate temperatures, genetic method development Thermus thermophilus

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
additional information
-
additional information thermodynamics of wild-type and mutant enzymes Thermus thermophilus
0.0011
-
DNA-RNA-DNA hybrid mutant A12S/K75M and A12S/K75M/A77P, pH 8.0, 30°C Thermus thermophilus
0.0013
-
DNA-RNA-DNA hybrid mutant A12S/A77P, pH 8.0, 30°C Thermus thermophilus
0.0015
-
DNA-RNA-DNA hybrid mutant A12S, pH 8.0, 30°C Thermus thermophilus
0.002
-
DNA-RNA-DNA hybrid mutant K75M/A77P, pH 8.0, 30°C Thermus thermophilus
0.0033
-
DNA-RNA-DNA hybrid mutant D134H and A77P, pH 8.0, 30°C Thermus thermophilus
0.0061
-
DNA-RNA-DNA hybrid mutant K75M, pH 8.0, 30°C Thermus thermophilus
0.0078
-
DNA-RNA-DNA hybrid wild-type enzyme, pH 8.0, 30°C Thermus thermophilus

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+
-
Thermus thermophilus

Organism

Organism UniProt Comment Textmining
Thermus thermophilus
-
type I enzyme, gene rnhA
-
Thermus thermophilus HB8 / ATCC 27634 / DSM 579
-
type I enzyme, gene rnhA
-

Purification (Commentary)

Purification (Comment) Organism
recombinant wild-type and mutant enzymes from Escherichia coli Thermus thermophilus

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
additional information
-
activity of wild-type and mutant enzymes at different temperatures Thermus thermophilus

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
DNA-RNA-DNA hybrid + H2O specific hydrolysis of the RNA strand of the hybrid Thermus thermophilus ?
-
?
DNA-RNA-DNA hybrid + H2O specific hydrolysis of the RNA strand of the hybrid Thermus thermophilus HB8 / ATCC 27634 / DSM 579 ?
-
?

Synonyms

Synonyms Comment Organism
ribonuclease HI
-
Thermus thermophilus
RNase HI
-
Thermus thermophilus

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
30
-
assay at Thermus thermophilus
60
-
assay at Thermus thermophilus

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
0.003
-
DNA-RNA-DNA hybrid mutant D134H, pH 8.0, 30°C Thermus thermophilus
0.075
-
DNA-RNA-DNA hybrid mutant A12S, pH 8.0, 30°C Thermus thermophilus
0.082
-
DNA-RNA-DNA hybrid wild-type enzyme, pH 8.0, 30°C Thermus thermophilus
0.122
-
DNA-RNA-DNA hybrid mutant A77P, pH 8.0, 30°C Thermus thermophilus
0.133
-
DNA-RNA-DNA hybrid mutant K75M, pH 8.0, 30°C Thermus thermophilus
0.2
-
DNA-RNA-DNA hybrid mutant A12S/K75M, pH 8.0, 30°C Thermus thermophilus
0.25
-
DNA-RNA-DNA hybrid mutant A12S/A77P, pH 8.0, 30°C Thermus thermophilus
0.33
-
DNA-RNA-DNA hybrid mutant K75M/A77P, pH 8.0, 30°C Thermus thermophilus
0.45
-
DNA-RNA-DNA hybrid mutant A12S/K75M/A77P, pH 8.0, 30°C Thermus thermophilus

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8
-
assay at Thermus thermophilus