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Literature summary for 3.2.1.23 extracted from

  • Rhimi, M.; Aghajari, N.; Jaouadi, B.; Juy, M.; Boudebbouze, S.; Maguin, E.; Haser, R.; Bejar, S.
    Exploring the acidotolerance of beta-galactosidase from Lactobacillus delbrueckii subsp. bulgaricus: an attractive enzyme for lactose bioconversion (2009), Res. Microbiol., 160, 775-784.
    View publication on PubMed

Application

Application Comment Organism
food industry the enzyme is used for hydrolysis of lactose extracted from whey or milk Lactobacillus delbrueckii

Cloned(Commentary)

Cloned (Comment) Organism
expressed in Escherichia coli MRS32 cells Lactobacillus delbrueckii

Protein Variants

Protein Variants Comment Organism
E491A the mutant shows wild type optimal temperature, but displays an optimal pH at 6.5-7.0 Lactobacillus delbrueckii

Inhibitors

Inhibitors Comment Organism Structure
Cu2+ 1 mM Cu2+ inhibits the activity more than 13fold Lactobacillus delbrueckii
EDTA 35% residual activity at 10 mM Lactobacillus delbrueckii
additional information not significantly inhibited by Fe2+, Ca2+, Mg2+, Zn2+, Ba2+, and Ni2+ Lactobacillus delbrueckii

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.16
-
2-nitrophenyl-beta-D-galactopyranoside wild type enzyme, in 100 mM sodium acetate buffer pH 5.5, at 45°C Lactobacillus delbrueckii
0.17
-
2-nitrophenyl-beta-D-galactopyranoside mutant enzyme E491A, in HEPES buffer pH 6.5, at 45°C Lactobacillus delbrueckii
0.94
-
lactose mutant enzyme E491A, in HEPES buffer pH 6.5, at 45°C Lactobacillus delbrueckii
0.98
-
lactose wild type enzyme, in 100 mM sodium acetate buffer pH 5.5, at 45°C Lactobacillus delbrueckii

Metals/Ions

Metals/Ions Comment Organism Structure
Co2+ the enzyme requires 1 mM Co2+ for optimal activity and thermostability Lactobacillus delbrueckii
Mg2+ the enzyme requires 1 mM Mn2+ for optimal activity and thermostability Lactobacillus delbrueckii

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
110000
-
4 * 110000, SDS-PAGE Lactobacillus delbrueckii
400000
-
gel filtration Lactobacillus delbrueckii

Natural Substrates/ Products (Substrates)

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

Organism

Organism UniProt Comment Textmining
Lactobacillus delbrueckii Q1G9Z4 strain ATCC 11842, subspecies Lactobacillus delbrueckii bulgaricus
-

Purification (Commentary)

Purification (Comment) Organism
ammonium sulfate precipitation and fast-performance liquid chromatography using an anion-exchange column equilibrated with 100 mM sodium acetate buffer (pH 5.5) Lactobacillus delbrueckii

Substrates and Products (Substrate)

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

Subunits

Subunits Comment Organism
homotetramer 4 * 110000, SDS-PAGE Lactobacillus delbrueckii

Synonyms

Synonyms Comment Organism
beta-gal
-
Lactobacillus delbrueckii
BGA
-
Lactobacillus delbrueckii

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
35 50
-
Lactobacillus delbrueckii

Temperature Stability [°C]

Temperature Stability Minimum [°C] Temperature Stability Maximum [°C] Comment Organism
40 65 the wild-type beta-galactosidase is fully stable at 40°C and 45°C for 16 h, respectively. At temperatures of 50, 55, 60 and 65°C wild type enzyme half-lives are 6, 3, 1.5 and 0.4 h respectively. Above 65°C occurs rapid inactivation with or without divalent ions Lactobacillus delbrueckii

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
45.7
-
lactose wild type enzyme, in 100 mM sodium acetate buffer pH 5.5, at 45°C Lactobacillus delbrueckii
46.3
-
lactose mutant enzyme E491A, in HEPES buffer pH 6.5, at 45°C Lactobacillus delbrueckii
47.2
-
2-nitrophenyl-beta-D-galactopyranoside wild type enzyme, in 100 mM sodium acetate buffer pH 5.5, at 45°C Lactobacillus delbrueckii
49.2
-
2-nitrophenyl-beta-D-galactopyranoside mutant enzyme E491A, in HEPES buffer pH 6.5, at 45°C Lactobacillus delbrueckii

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
5 5.5
-
Lactobacillus delbrueckii

pH Stability

pH Stability pH Stability Maximum Comment Organism
5.5
-
the wild type protein retains about 90% of its activity after 32 h at pH 5.5. At pH 5.0 and 6.0 the enzyme conserves more than 50% of its initial activity after 32 h of incubation, at pH 4.5, 6.5, 7.0 and 7.5 the enzyme half-lives are 24, 28, 20 and 18 h respectively Lactobacillus delbrueckii

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
46.6
-
lactose wild type enzyme, in 100 mM sodium acetate buffer pH 5.5, at 45°C Lactobacillus delbrueckii
47
-
lactose mutant enzyme E491A, in HEPES buffer pH 6.5, at 45°C Lactobacillus delbrueckii
289.4
-
2-nitrophenyl-beta-D-galactopyranoside mutant enzyme E491A, in HEPES buffer pH 6.5, at 45°C Lactobacillus delbrueckii
295
-
2-nitrophenyl-beta-D-galactopyranoside wild type enzyme, in 100 mM sodium acetate buffer pH 5.5, at 45°C Lactobacillus delbrueckii