  Serum albumin, recognized mainly for its capacity to act as a carrier protein
for many compounds, can also actively transform some organic molecules. As a
starting point in this study we consider esterase-like activity of bovine serum
albumin (BSA) toward p-nitrophenyl acetate (p-NPA). Our results reveal that the
reaction goes beyond ester hydrolysis step. In fact the transformation product,
p-nitrophenol (p-NP), becomes a substrate for further reaction with BSA in
which its nitro group in subtracted and released in the form of HNO2. Spectral
data indicate that this cascade of events proceeds through formation of
phenoxyl radical via proton coupled electron transport (PCET) between OH group
of p-NP and imidazole ring of histidine from the protein. Furthermore, the
effect of application of electromagnetic radiation in the infrared range,
suggests that this remote physical trigger can support interactions based on
PCET mechanism by acting on polarization and mutual alignment of water dipoles
serving as effective water wires.
