Literature summary for 3.2.1.22 extracted from

Chakladar, S.; Cheng, L.; Choi, M.; Liu, J.; Bennet, A.J.
Mechanistic evaluation of MelA alpha-galactosidase from Citrobacter freundii: a family 4 glycosyl hydrolase in which oxidation is rate-limiting (2011), Biochemistry, 50, 4298-4308.

Search for more literature for 3.2.1.22

Activating Compound

Activating Compound	Comment	Organism	Structure
2-mercaptoethanol	required for enzymatic activity	Citrobacter freundii

Metals/Ions

Metals/Ions	Comment	Organism	Structure
Mn2+	required for enzymatic activity	Citrobacter freundii

Organism

Organism	UniProt	Comment	Textmining
Citrobacter freundii	-	-	-

Reaction

Reaction	Comment	Organism	Reaction ID
raffinose + H2O = sucrose + alpha-D-galactopyranose	the recombinant enzyme catalyzes the hydrolysis of phenyl R-galactosides via a redox elimination-addition mechanism involving oxidation of the hydroxyl group at C-3 and elimination of phenol across the C-1-C-2 bond to give an enzyme-bound glycal intermediate	Citrobacter freundii	a

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
4-nitrophenyl-alpha-D-galactopyranoside + H2O	-	Citrobacter freundii	4-nitrophenol + alpha-D-galactopyranose	-	?

Synonyms

Synonyms	Comment	Organism
alpha-galactosidase	-	Citrobacter freundii
MelA	-	Citrobacter freundii

Temperature Optimum [°C]

Temperature Optimum [°C]	Temperature Optimum Maximum [°C]	Comment	Organism
37	-	assay at	Citrobacter freundii

Turnover Number [1/s]

Turnover Number Minimum [1/s]	Turnover Number Maximum [1/s]	Substrate	Comment	Organism	Structure
0.12	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 4.5, 37°C	Citrobacter freundii
0.23	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 9.0, 37°C	Citrobacter freundii
0.3	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 6.7, 37°C	Citrobacter freundii
0.62	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 8.7, 37°C	Citrobacter freundii
1.05	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 7.1, 37°C	Citrobacter freundii
1.37	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 8.4, 37°C	Citrobacter freundii
1.68	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 7.5, 37°C	Citrobacter freundii
1.75	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 8.0, 37°C	Citrobacter freundii
2.07	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 7.8, 37°C	Citrobacter freundii

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
7.5	-	assay at	Citrobacter freundii

Cofactor

Cofactor	Comment	Organism	Structure
NAD+	required for enzymatic activity	Citrobacter freundii

kcat/KM [mM/s]

kcat/KM Value [1/mMs^-1]	kcat/KM Value Maximum [1/mMs^-1]	Substrate	Comment	Organism	Structure
0.091	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 4.5, 37°C	Citrobacter freundii
0.81	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 6.7, 37°C	Citrobacter freundii
0.96	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 9.0, 37°C	Citrobacter freundii
2.7	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 7.1, 37°C	Citrobacter freundii
5	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 8.7, 37°C	Citrobacter freundii
5.8	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 7.5, 37°C	Citrobacter freundii
8.9	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 8.0, 37°C	Citrobacter freundii
9.9	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 7.8, 37°C	Citrobacter freundii
15.6	-	4-nitrophenyl-alpha-D-galactopyranoside	pH 8.4, 37°C	Citrobacter freundii

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Release 2023.1 (January 2023)