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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1rpt

E.C. nameacid phosphatase
SpeciesRattus norvegicus (Rat)
E.C. Number (IntEnz) 3.1.3.2
CSA Homologues of 1rptThere are 24 Homologs
CSA Entries With UniProtID P20646
CSA Entries With EC Number 3.1.3.2
PDBe Entry 1rpt
PDBSum Entry 1rpt
MACiE Entry 1rpt

Literature Report

IntroductionHigh molecular weight acid phosphatases (HAPs) form a subclass of phosphomonoesterases which are found in locations as diverse as wheat germ, mammalian prostate tissue, and as extracellular or periplasmic enzymes in fungi and bacteria. To date, the only HAP structures available are the rat prostatic enzyme, and phytase from the fungus Aspergillus ficuum. This latter enzyme is essential in metabolising phytate, the major phosphorous storage form in plant seeds.
MechansimHydrolysis is effected in two steps, starting with a nucleophilic attack of the enzyme on the phosphate group of the substrate to produce an enzyme-phosphate adduct. The phosphorylated residue has been identified as His12 (numbering from rat enzyme) and Asp258 protonates the leaving group of the substrate. The second step involves the attack of water on the phosphorous atom to release inorganic phosphate from the enzyme, in such a way as to return to the original configuration of the phosphorous atom. Crystal structures with vanadate, a believed transition state analogue, indicate that positively charged His and Arg residues in the active site are involved in correctly orientating the phosphate group and transition state stabilisation.
Reaction

Catalytic Sites for 1rpt

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
ArgA1546macie:sideChain
HisA257288macie:sideChain
ArgA79110macie:sideChain
AspA258289macie:sideChain
ArgA1142macie:sideChain
HisA1243macie:sideChain

Literature References

Notes:The high molecular weight acid phosphatases have a distinct mechanism from other acid phosphatases; e.g. they retain the configuration of the substrate phosphorous atom while the purple acid phosphatases reverse it, and use a phospho-histidine intermediate. Evidently nature has 'discovered' multiple ways of catalysing this important reaction.
Lindqvist Y.
Crystal structures of rat acid phosphatase complexed with the transition-state analogs vanadate and molybdate. Implications for the reaction mechanism
Eur J Biochem 1994 221 139-142
PubMed: 8168503
Zhang M.
Crystal structure of bovine low molecular weight phosphotyrosyl phosphatase complexed with the transition state analog vanadate
Biochemistry 1997 36 15-23
PubMed: 8993313
Kostrewa D.
Crystal structure of phytase from Aspergillus ficuum at 2.5 A resolution
Nat Struct Biol 1997 4 185-190
PubMed: 9164457
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