Glu‐256 is a main structural determinant for oligomerisation of human arginase I

FEBS Letters

Alonso, Juan Carlos¹  Centeno, Francisco¹  Marcos, Carlos F.²  Mora, Alfonso¹  Sabio, Guadalupe¹  Rangel, Marı́adel Ara¹  Soler, Germán¹  Quesada, Alberto¹ 

[1] Departamento de Bioquı́mica y Biologı́a Molecular, Facultad de Veterinaria, Universidad de Extremadura, Av. Universidad s/n, 10071 Cáceres, Spain;Departamento de Quı́mica Orgánica, Facultad de Veterinaria, Universidad de Extremadura, Av. Universidad s/n, 10071 Cáceres, Spain

关键词: Arginase monomer;    Quaternary structure;    Site-directed mutagenesis;    Mn2+ cofactor;   

DOI  :  10.1016/S0014-5793(01)02650-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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 Mn²⁺; 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.

【 授权许可】

Unknown