AC MF_01433; DC Protein; auto TR HAMAP; MF_01433; -; 1; level=0 XX Names: Pyrim_hydro_RihB XX ID RIHB DE RecName: Full=Pyrimidine-specific ribonucleoside hydrolase RihB; DE EC=3.2.2.8; DE AltName: Full=Cytidine/uridine-specific hydrolase; GN Name=rihB; XX CC -!- FUNCTION: Hydrolyzes cytidine or uridine to ribose and cytosine or CC uracil, respectively. Has a clear preference for cytidine over uridine. CC Strictly specific for ribonucleosides. CC -!- CATALYTIC ACTIVITY: CC Reaction=a pyrimidine ribonucleoside + H2O = a pyrimidine nucleobase + CC D-ribose; Xref=Rhea:RHEA:56816, ChEBI:CHEBI:15377, ChEBI:CHEBI:26432, CC ChEBI:CHEBI:47013, ChEBI:CHEBI:141014; EC=3.2.2.8; case CC -!- COFACTOR: CC Name=Ca(2+); Xref=ChEBI:CHEBI:29108; CC Note=Binds 1 Ca(2+) ion per monomer.; end case CC -!- SUBUNIT: Homotetramer. CC -!- SIMILARITY: Belongs to the IUNH family. RihB subfamily. XX DR PROSITE; PS01247; IUNH; 1; trigger=no DR Pfam; PF01156; IU_nuc_hydro; 1; trigger=no XX KW Glycosidase KW Hydrolase case KW Calcium KW Metal-binding end case XX case GO GO:0005509; F:calcium ion binding end case GO GO:0050263; F:ribosylpyrimidine nucleosidase activity GO GO:0006206; P:pyrimidine nucleobase metabolic process XX FT From: RIHB_ECOLI (P33022) FT ACT_SITE 11 FT /note="Proton acceptor" FT Condition: [DE] FT BINDING 11 FT /ligand="Ca(2+)" FT /ligand_id="ChEBI:CHEBI:29108" FT Group: 1; Condition: [DE] FT BINDING 16 FT /ligand="Ca(2+)" FT /ligand_id="ChEBI:CHEBI:29108" FT Group: 1; Condition: D FT BINDING 124 FT /ligand="Ca(2+)" FT /ligand_id="ChEBI:CHEBI:29108" FT Group: 1; Condition: V FT BINDING 240 FT /ligand="Ca(2+)" FT /ligand_id="ChEBI:CHEBI:29108" FT Group: 1; Condition: D FT BINDING 227 FT /ligand="substrate" FT Condition: Q FT BINDING 239 FT /ligand="substrate" FT Condition: H XX Size: 313-313; Related: None; Template: P33022; Scope: Bacteria; Enterobacteriaceae Fusion: Nter: None Cter: None Duplicate: None Plasmid: None Comments: None XX # Revision 1.19 2022/11/19 //