Importance of arginine residues in the determination of the biological activity of human corticosteroid-binding globulin.
The binding activity of human corticosteroid-binding globulin (CBG) is pH dependent and governed in alkaline pH ranges by the pK of arginine. No essential arginine residues is located in the binding site. The loss of biological activity is rapid and complete as soon as one arginine residue is modified by phenylglyoxal. There is also a transconformation of the CBG molecule. Therefore the surprising stability of CBG up to pH 11.5 may be explained by a large dependence of the CBG tertiary structure on the integrity of one arginine residue : as long as the ionized state of this single residue is not changed (pH less than pK of the guanidyl group) the tertiary structure of the biologically active CBG is maintained in alkaline pH ranges.
D001120:Arginine; D002942:Circular Dichroism; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010658:Phenylglyoxal / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D014156:Transcortin / Q000378:metabolism*
D014156:Transcortin; D001120:Arginine; D010658:Phenylglyoxal; D006854:Hydrocortisone