UniProt functional annotation for P39130

UniProt code: P39130.

Organism:		Bacillus subtilis (strain 168).
Taxonomy:		Bacteria; Firmicutes; Bacilli; Bacillales; Bacillaceae; Bacillus.
Function:		Alpha-galacturonidase able to catalyze the hydrolysis of the chromogenic substrate p-nitrophenyl-alpha-D-galacturonic acid (pNPalphaGalUA), and of the probable natural substrate alpha-1,4-di- galacturonate (GalUA(2)). Can neither hydrolyze pNPbetaGalUA, nor the stereoisomeric pNPalphaGlcUA. Does not display alpha- or beta- glucosidase activity as it fails to hydrolyze melibiose, raffinose, lactose and the chromogenic analogs, pNPalphaGal and pNPbetaGal. Cannot use the following compounds as substrates: pNP-N-acetyl-alpha- and beta-D-galactosaminide, pNP-N-acetyl-alpha- and beta-D-glucosaminide, pNP-alpha-L- and beta-L-arabinopyranoside, pNP-alpha- and beta-D- glucuronide, pNP-alpha- and beta-D-glucopyranoside, pNP-alpha- and beta-D-glucopyranoside 6-phosphate, pNP-alpha-D-galactopyranoside 6- phosphate and oNP-beta-D-galactopyranoside 6-phosphate. {ECO:0000269|PubMed:23416295}.
Catalytic activity:		Reaction=[(1->4)-alpha-D-galacturonosyl](n) + H2O = [(1->4)-alpha-D- galacturonosyl](n-1) + alpha-D-galacturonate; Xref=Rhea:RHEA:14117, Rhea:RHEA-COMP:14570, Rhea:RHEA-COMP:14572, ChEBI:CHEBI:15377, ChEBI:CHEBI:58658, ChEBI:CHEBI:140523; EC=3.2.1.67; Evidence={ECO:0000269|PubMed:23416295};
Cofactor:		Name=NAD(+); Xref=ChEBI:CHEBI:57540; Evidence={ECO:0000305|PubMed:23416295};
Cofactor:		Name=Mn(2+); Xref=ChEBI:CHEBI:29035; Evidence={ECO:0000269|PubMed:23416295}; Note=Binds 1 Mn(2+) ion per subunit. Although a Mg(2+) ion is seen in the structure, galacturonidase activity was shown using manganese (PubMed:23416295). {ECO:0000269|PubMed:23416295};
Biophysicochemical properties:		Kinetic parameters: KM=0.62 uM for pNPalphaGalUA (at about 37 degrees Celsius) {ECO:0000269|PubMed:23416295}; Vmax=4.33 umol/min/mg enzyme with pNPalphaGalUA as substrate (at about 37 degrees Celsius) {ECO:0000269|PubMed:23416295}; Note=kcat is 3.6 sec(-1) with pNPalphaGalUA as substrate (at about 37 degrees Celsius).;
Subunit:		Homotetramer. {ECO:0000269|PubMed:23416295, ECO:0000269|Ref.4}.
Similarity:		Belongs to the glycosyl hydrolase 4 family. {ECO:0000305}.

Annotations taken from UniProtKB at the EBI.