Electrochemical reduction and oxidation signals of angiotensin peptides. Role of individual amino acid residues

• Arginine participates in catalytic hydrogen evolution reaction (CHER) of peptides.
• At pH 7 participation of histidine in CHER of angiotensin peptides is negligible.
• Histidine in angiotensin peptides produces no oxidation peak at carbon electrode.

Chronopotentiometric stripping (CPS) peak H in proteins is due to the catalytic hydrogen evolution reaction (CHER) involving amino acid residues. This peak is sensitive to changes in protein structures, representing a new tool in protein research. Here we show on the ground of studies of CPS behavior of four angiotensin peptides that at neutral pH arginine plays a critical role in CHER at Hg electrode, while participation of histidine residues in this reaction is very weak. At carbon electrode tyrosine residues produce an oxidation peak close to 0.7 V but the presence of histidine in angiotensins is not manifested by any oxidation peak.