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Properties of N‐terminus truncated and C‐terminus mutated muscle acylphosphatases
Author(s) -
Taddei Niccolò,
Modesti Alessandra,
Bucciantini Monica,
Stefani Massimo,
Magherini Francesca,
Vecchi Manuela,
Raugei Giovanni,
Ramponi Giampietro
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00236-3
Subject(s) - n terminus , c terminus , chemistry , biochemistry , genetics , biology , peptide sequence , amino acid , gene
Enzymatic activity and structure of N‐terminus truncated and C‐terminus substituted muscle acylphosphatase mutants were investigated by kinetic studies under different conditions and 1 H NMR spectroscopy, respectively. The N‐terminus truncated mutant lacked the first six residues (Δ6), whereas arginine 97 and tyrosine 98 were replaced by glutamine giving two C‐terminus substituted mutants (R97Q and Y98Q, respectively). All acylphosphatase forms were obtained by modifications of a synthetic gene coding for the human muscle enzyme which was expressed in E. coli . The Δ6 deletion mutant elicited a reduced specific activity and a native‐like structure. The kinetic and structural properties of R97Q and Y98Q mutants indicate a possible role of Arg‐97 in the stabilisation of the active site correct conformation, most likely via back‐bone and side chain interactions with Arg‐23, the residue involved in phosphate binding by the enzyme. This study also suggests a possible involvement of Tyr‐98 in the stabilisation of the acylphosphatase overall structure.