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Literature summary for 2.7.1.6 extracted from

  • Reinhardt, L.A.; Thoden, J.B.; Peters, G.S.; Holden, H.M.; Cleland, W.W.
    pH-rate profiles support a general base mechanism for galactokinase (Lactococcus lactis) (2013), FEBS Lett., 587, 2876-2881.
    View publication on PubMedView publication on EuropePMC
Search for more literature for 2.7.1.6

Protein Variants

Protein Variants Comment Organism
D183A inactive Lactococcus lactis
D183N inactive Lactococcus lactis
R36A 100fold decrease in activity Lactococcus lactis
R36N 100fold decrease in activity Lactococcus lactis

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.018
-
 ATP mutant R36K, pH 8.0, 24°C Lactococcus lactis
0.053
-
 ATP wild-type, pH 8.0, 24°C Lactococcus lactis
0.14
-
 ATP mutant R36A, pH 8.0, 24°C Lactococcus lactis
0.48
-
 alpha-D-galactose wild-type, pH 8.0, 24°C Lactococcus lactis
1
-
 alpha-D-galactose mutant R36K, pH 8.0, 24°C Lactococcus lactis
1.8
-
 alpha-D-galactose mutant R36A, pH 8.0, 24°C Lactococcus lactis

Organism

Organism UniProt Comment Textmining
Lactococcus lactis
-
-
-

Reaction

Reaction Comment Organism Reaction ID
ATP + alpha-D-galactose = ADP + alpha-D-galactose 1-phosphate mechanism of the reaction is sequential in both directions. Residue Asp183 acts as a catalytic base that deprotonates the C1 hydroxyl group of galactose. The pH-kcat profile of the synthesis of galactose 1-phosphate has a pKa of 6.9 likely due to Asp183. The pH-kcat/KGal profile of the reverse reaction lacks a key pKa required for a direct proton transfer mechanism. Arg36 may lower the pKa of the C1 hydroxyl to facilitate deprotonation Lactococcus lactis
a

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
0.0043
-
 mutant R36K, synthesis of ATP, pH 8.0, 24°C Lactococcus lactis
0.0067
-
 mutant R36A, synthesis of ATP, pH 8.0, 24°C Lactococcus lactis
0.08
-
 mutant R36A, synthesis of galactose 1-phosphate, pH 8.0, 24°C Lactococcus lactis
0.1
-
 mutant R36K, synthesis of galactose 1-phosphate, pH 8.0, 24°C Lactococcus lactis
0.43
-
 wild-type, synthesis of ATP, pH 8.0, 24°C Lactococcus lactis
11.5
-
 wild-type, synthesis of galactose 1-phosphate, pH 8.0, 24°C Lactococcus lactis

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
ADP + alpha-D-galactose 1-phosphate
-
 Lactococcus lactis ATP + alpha-D-galactose
-
 r
ATP + alpha-D-galactose
-
 Lactococcus lactis ADP + alpha-D-galactose 1-phosphate
-
 r
additional information mechanism of the reaction is sequential in both directions. Residue Asp183 acts as a catalytic base that deprotonates the C1 hydroxyl group of galactose. The pH-kcat profile of the synthesis of galactose 1-phosphate has a pKa of 6.9 likely due to Asp183. The pH-kcat/KGal profile of the reverse reaction lacks a key pKa required for a direct proton transfer mechanism. Arg36 may lower the pKa of the C1 hydroxyl to facilitate deprotonation Lactococcus lactis ?
-
 ?

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
0.15
-
 alpha-D-galactose mutant R36A, pH 8.0, 24°C Lactococcus lactis
0.45
-
 alpha-D-galactose mutant R36K, pH 8.0, 24°C Lactococcus lactis
11
-
 alpha-D-galactose wild-type, pH 8.0, 24°C Lactococcus lactis

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
0.081
-
 alpha-D-galactose mutant R36A, pH 8.0, 24°C Lactococcus lactis
0.45
-
 alpha-D-galactose mutant R36K, pH 8.0, 24°C Lactococcus lactis
1
-
 ATP mutant R36A, pH 8.0, 24°C Lactococcus lactis
23
-
 alpha-D-galactose wild-type, pH 8.0, 24°C Lactococcus lactis
25
-
 ATP mutant R36K, pH 8.0, 24°C Lactococcus lactis
207
-
 ATP wild-type, pH 8.0, 24°C Lactococcus lactis