Dc. Benjamin et al., Increasing the thermal stability of euphauserase - A cold-active and multifunctional serine protease from Antarctic krill, EUR J BIOCH, 268(1), 2001, pp. 127-131
A molecular model of Antarctic krill euphauserase based on the known crysta
l structure of its fiddler crab analog, collagenase I, indicates that the c
ore structure of these enzymes is almost identical. Euphauserase is a cold-
active and thermally sensitive enzyme with a high affinity for Lys, Arg and
large hydrophobic amino acids. Residue Phe137 in euphauserase, localized i
n loop D (autolysis loop), is highly exposed on the surface of the molecule
. Therefore, it appeared to be an easy target for autolysis. The broadly sp
ecific euphauserase has a low affinity for negatively charged residues. In
order to increase the stability of the enzyme, two mutants were created in
which residue Phe137 was replaced by a Glu and an Asp residue. Both mutatio
ns resulted in increased stability of the recombinant euphauserase towards
thermal inactivation.