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Glu‐256 is a main structural determinant for oligomerisation of human arginase I
Author(s) -
Sabio Guadalupe,
Mora Alfonso,
Rangel Marı́adel Ara,
Quesada Alberto,
Marcos Carlos F.,
Alonso Juan Carlos,
Soler Germán,
Centeno Francisco
Publication year - 2001
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/s0014-5793(01)02650-3
Subject(s) - arginase , protein quaternary structure , chemistry , biochemistry , arginine , mutant , enzyme , lysine , protein subunit , monomer , residue (chemistry) , amino acid , organic chemistry , gene , polymer
One determinant that could play a role in the quaternary structure of human arginase is the pair of salt links between the strictly conserved residues R255 from one monomer and E256 from every adjacent subunit. In this work, the ionic interaction between monomers was disrupted by expressing a human arginase where Glu‐256 had been substituted by Gln. Biochemical analyses of the mutant protein showed that: (i) it shares the wild‐type kinetic parameters of the arginine substrate; (ii) E256Q arginase behaves as a monomer by gel filtration; (iii) it is drastically inactivated by dialysis in the presence of EDTA, an inhibitory effect which is reversed by addition of Mn 2+ ; and (iv) the mutant enzyme loses thermal stability. The lack of oligomerisation for E256Q arginase and the conservation of E256 throughout evolution of the protein family suggest that this residue is involved in the quaternary structure of arginases.