New insights into the mechanism of purple acid phosphatase through (1)H NMR spectroscopy of the recombinant human enzyme.
J Am Chem Soc
; 124(47): 13974-5, 2002 Nov 27.
Article
em En
| MEDLINE
| ID: mdl-12440878
ABSTRACT
Proton NMR spectra of FeIII-FeII recombinant single polypeptide human PAP (recHPAP) have been measured at, above, and below its pH optimum, as have the spectra of inhibited forms containing fluoride and phosphate, analogues of the substrates hydroxide and phosphate esters, respectively. The results demonstrate that binding of inhibitory anions to the dinuclear mixed-valent site of recHPAP is controlled by protonation of a ligand to the dinuclear center. Thus, the group that is responsible for pKa,1 in the enzymatic activity versus pH profile functions as a "gatekeeper", whose protonation state controls anion binding to the mixed-valent dinuclear site. The correlation between the pKa values observed in kinetics studies and for the spectroscopic changes strongly suggests that this group is the nucleophilic hydroxide that attacks the phosphate ester substrate.
Buscar no Google
Base de dados:
MEDLINE
Assunto principal:
Fosfatase Ácida
/
Glicoproteínas
Idioma:
En
Ano de publicação:
2002
Tipo de documento:
Article