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Search The CSA
PDB ID
UNIPROT ID
EC Number

Catalytic Site Atlas

CSA LITERATURE entry for 4kbp

E.C. nameacid phosphatase
SpeciesPhaseolus vulgaris (Red kidney bean)
E.C. Number (IntEnz) 3.1.3.2
CSA Homologues of 4kbp1kbp,1xzw,2qfp,2qfr,3kbp,
CSA Entries With UniProtID P80366
CSA Entries With EC Number 3.1.3.2
PDBe Entry 4kbp
PDBSum Entry 4kbp
MACiE Entry M0043

Literature Report

IntroductionThese enzymes are given a distinctive purple colour by their dinuclear Fe(III)-Me(II) centres (where Me can be Fe or Zn), and are widely distributed throughout evolution. They function at pH 4 to 7 to hydrolyse a diverse set of substrates including phosphomonoesters of sugars and proteins, and anhydrides such as ATP.
MechansimOn the basis of structural studies with bound phosphate and tungstate (inhibitor), and the observed inversion of the phosphorous configuration during catalysis, an SN2-type mechanism is proposed for PAP. The substrate phosphate is bound to the Me(II) ion via one of the non-esterified oxygen atoms and oriented by His202 and His296 (numbering for kidney bean enzyme) for in-line attack of an Fe(III)-bound hydroxide ion from a position opposite the esterified oxygen. These residues and the metal ions are presumed to stabilise the pentaco-ordinate transition state. Tentatively, His296 may then act as a general acid to protonate the leaving group, followed by the attack of a water molecule on the Fe(III) atom to release the inorganic phosphate.
Reaction

Catalytic Sites for 4kbp

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
HisA296296macie:sideChain
HisA202202macie:sideChain
HisA295295macie:sideChain

Annotated By Reference To The Literature - Site 2 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
HisB296296macie:sideChain
HisB202202macie:sideChain
HisB295295macie:sideChain

Annotated By Reference To The Literature - Site 3 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
HisC296296macie:sideChain
HisC202202macie:sideChain
HisC295295macie:sideChain

Annotated By Reference To The Literature - Site 4 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
HisD296296macie:sideChain
HisD202202macie:sideChain
HisD295295macie:sideChain

Literature References

Notes:The purple acid phosphatases share a well conserved structural motif which is not recognised by linear sequence motifs such as those in PROSITE. The enzymes from each EC number have different folds; their CATH numbers are each unique to these enzymes. This combined with their wide distribution and broad substrate range suggest that these enzymes have greatly diverged from a very old common ancestor. The fact that His296 is not conserved calls into question its tentative role in catalysis, although it is suggested that an Asn residue may be able to substitute for it in other enzymes.
Klabunde T
Mechanism of Fe(III)-Zn(II) purple acid phosphatase based on crystal structures.
J Mol Biol 1996 259 737-748
PubMed: 8683579
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