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Literature summary for 3.2.1.23 extracted from

  • Lo, S.; Dugdale, M.L.; Jeerh, N.; Ku, T.; Roth, N.J.; Huber, R.E.
    Studies of Glu-416 variants of beta-galactosidase (E. coli) show that the active site Mg2+ is not important for structure and indicate that the main role of Mg2+ is to mediate optimization of active site chemistry (2010), Protein J., 29, 26-31.
    View publication on PubMed

Crystallization (Commentary)

Crystallization (Comment) Organism
mutant enzymes E416Q and E416V Escherichia coli

Protein Variants

Protein Variants Comment Organism
E416Q the mutant enzyme does not have a Mg2+ bound at the active site even at high Mg2+ concentrations (200 mM), low catalytic activity and the pH profile is very different from that of the native enzyme Escherichia coli
E416V the mutant enzyme does not have a Mg2+ bound at the active site even at high Mg2+ concentrations (200 mM), low catalytic activity and the pH profile is very different from that of the native enzyme Escherichia coli

Inhibitors

Inhibitors Comment Organism Structure
D-galactonolactone
-
Escherichia coli
D-galactose
-
Escherichia coli
lactose
-
Escherichia coli

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.12
-
2-nitrophenyl-beta-D-galactopyranoside native enzyme Escherichia coli
9.5
-
2-nitrophenyl-beta-D-galactopyranoside mutant enzyme E416V Escherichia coli
18
-
2-nitrophenyl-beta-D-galactopyranoside mutant enzyme E416Q Escherichia coli

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+ beta-galactosidase requires Mg2+ for full catalytic activity, one Mg2+ is at each active site but 3-4 others bind to other parts of each subunit Escherichia coli

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
lactose + H2O Escherichia coli
-
D-galactose + D-glucose
-
?
lactose + H2O Escherichia coli LMG194
-
D-galactose + D-glucose
-
?

Organism

Organism UniProt Comment Textmining
Escherichia coli P00722
-
-
Escherichia coli LMG194 P00722
-
-

Purification (Commentary)

Purification (Comment) Organism
ProBond Ni column chromatography Escherichia coli

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2-nitrophenyl beta-D-galactopyranoside + H2O
-
Escherichia coli 2-nitrophenol + beta-D-galactose
-
?
2-nitrophenyl beta-D-galactopyranoside + H2O
-
Escherichia coli LMG194 2-nitrophenol + beta-D-galactose
-
?
lactose + H2O
-
Escherichia coli D-galactose + D-glucose
-
?
lactose + H2O
-
Escherichia coli LMG194 D-galactose + D-glucose
-
?

Synonyms

Synonyms Comment Organism
beta-gal
-
Escherichia coli
BGA
-
Escherichia coli

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
54
-
2-nitrophenyl-beta-D-galactopyranoside mutant enzyme E416Q Escherichia coli
81
-
2-nitrophenyl-beta-D-galactopyranoside mutant enzyme E416V Escherichia coli
620
-
2-nitrophenyl-beta-D-galactopyranoside native enzyme Escherichia coli

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
0.6
-
D-galactonolactone native enzyme Escherichia coli
1
-
lactose native enzyme Escherichia coli
4.9
-
D-galactonolactone mutant enzyme E416V Escherichia coli
24
-
D-galactose native enzyme Escherichia coli
24
-
D-galactonolactone mutant enzyme E416Q Escherichia coli
107
-
lactose mutant enzyme E416V Escherichia coli
154
-
lactose mutant enzyme E416Q Escherichia coli
211
-
D-galactose mutant enzyme E416V Escherichia coli
220
-
D-galactose mutant enzyme E416Q Escherichia coli