Yes, indeed Andrey. And this results from resonance (tautomerization) of the guanidinium group.
Regards, Nadir Mrabet Pr. Nadir T. Mrabet Structural & Molecular Biochemistry N-gere - INSERM U-954 University of Lorraine, Nancy School of Sciences and Technologies & School of Medicine 9, Avenue de la Foret de Haye, BP 184 54505 Vandoeuvre-les-Nancy Cedex France Phone: +33 (0)3.83.68.32.73 Fax: +33 (0)3.83.68.32.79 E-mail: Nadir.Mrabet <at> univ-lorraine.fr On 08/10/2013 18:01, Andrey Feklistov wrote:
Hi Jan, please note, Arg-Arg proximity is not always repulsive: guanidinium groups can associate bridged by H-bonds and interactions with water molecules or neighboring amino acids. There are many examples of these unusual Arg formations, see for reference: Neves, Yeager and Abagyan (2012) "Unusual Arginine Formations in Protein Function and Assembly: Rings, Strings and Stacks", J. Phys. Chem. B 116, 7006−7013 Hope this is helpful, Andrey
