Arginine-23 is involved in the catalytic site of muscle acylphosphatase

Niccolò Taddei, Massimo Stefani, Manuela Vecchi, Alessandra Modesti, Giovanni Raugei, Monica Bucciantini, Francesca Magherini, Giampietro Ramponi

Research output: Contribution to journalArticlepeer-review

Abstract

Three mutants of human muscle acylphosphatase in which arginine-23 was replaced by glutamine, histidine and lysine, respectively, were prepared by oligonucleotide-directed mutagenesis of a synthetic gene coding for the enzyme. All mutants, purified by affinity chromatography, were almost completely unable to catalyze the hydrolysis of the substrate. 1H-NMR spectroscopy experiments showed the absence of any major conformational changes of the three mutants with respect to the wild-type recombinant enzyme. Equilibrium dialysis experiments demonstrated that the mutated proteins lost the ability of binding inorganic phosphate, a competitive inhibitor of the enzyme. These results strongly support an involvement of arginine-23 at the phosphate binding-site of acylphosphatase, confirming the hypothesis of the existence of a phosphate binding structural motif recently proposed by other authors.

Original languageEnglish
Pages (from-to)75-80
Number of pages6
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Volume1208
Issue number1
DOIs
Publication statusPublished - Sep 21 1994

Keywords

  • (Muscle)
  • Acylphosphatase
  • Acylphosphatase active site
  • NMR, H-
  • Recombinant protein
  • Site-directed mutagenesis

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology
  • Structural Biology

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