Biologia, Bratislava, 57/Suppl. 11: 213-219, 2002.
ISSN 0006-3088 (Biologia).
Structural determinants of cold adaptation and stability in a
Laboratory of Biochemistry, Institute of Chemistry B6, University of Liege, B-4000 Liege, Belgium; tel.: ++ 32 4 366 33 43, fax: ++ 32 4 366 33 64, e-mail: firstname.lastname@example.org
: / :
Bratislava, 57/Suppl. 11: xxx-xxx, 2002; ISSN
0006-3088 (Biologia). ISSN 1335-6399 (Biologia. Section Cellular and Molecular
words: ex tremophiles, protein engineering, microcalorimetry. _____________________ *Corresponding
a-amylase from an Antarctic
bacterium is the largest known protein that unfolds reversibly according to a
two-state transition as shown by differential scanning
calorimetry. Mutants of this enzyme were produced, carrying intended additional
weak interactions of a type found in thermostable a-amylases. It is shown that
single amino ity
and reversibility of unfolding, the thermal inactivation rate constant, and the
kinetic parameters kcat and Km. Although all mutations
were located far from the active site, their overall trend is to decrease both
kcat and Km probably by rigidifying
the molecule and to protect mutants against thermal inactivation.