Hydrogen bonding interactions of N⁸-Gsp with protein residues.

The inset shows a conserved water molecule in a small pocket near the glutathionyl moiety of Gsp. (magenta: N⁸-Gsp, blue: residues from flexible loop region, green: residues from rigid part of Gsp binding pocket, orange dotted lines: hydrogen bonds). None of the arginine residues directly interacts with the substrate, but both contribute to the stabilisation of the Gsp binding pocket: Arg222 by interacting with Glu614 and Arg613 by interacting with Ser624, Leu274 (not shown) and Glu355.