Energetics and structural parameters for the lowest-energy conformers of angiotensin II protomers.

In each row the following information is reported: protonation pattern (first column); energy difference with respect to the most stable protomer ( in kJ/mol); (intrinsic) internal energy variation (), proton affinity (PA) and gas-phase basicity (GPB) relative to the most favourable protomer (see text for a definition of these quantities; all values are in kJ/mol); ionized residues (IR); salt-bridges (SB); hydrogen bonds between salt-bridged residues (sHB); ionized hydrogen bonds where either the donor or the acceptor is ionized, A or D H-bonds (iHB); neutral hydrogen bonds (HB). Hydrogen bonds are identified according to the donor-acceptor () distance and the donor-acceptor H-bond angle (). The following geometric criterion was adopted: Å and . A salt-bridge is formed if the distance between any oxygen atom of the acidic residue and any protonable nitrogen atom of the basic residue is less than 4.0 Å.