Περίληψη:
Concanavalin A (Con A) is the best known plant lectin, with important
biological properties arising from its specific saccharide-binding
ability. Its exact biological role still remains unknown. The complex of
Con A with 4’-methylumbelliferyl-alpha-D-glucopyranoside (alpha-MUG) has
been crystallized in space group P2(1) with cell dimensions a = 81.62
Angstrom, b = 128.71 Angstrom, c = 82.23 Angstrom, and beta = 118.47
degrees. X-ray diffraction intensities to 2.78 Angstrom have been
collected. The structure of the complex was solved by molecular
replacement ansi refined by simulated annealing methods to a
crystallographic R-factor value of 0.182 and a free-R-factor value of
0.216. The asymmetric unit contains four subunits arranged as a
tetramer, with approximate 222 symmetry, A saccharide molecule is bound
in the sugar-binding site at the surface of each subunit, with the
nonsugar (aglycon) part adopting a different orientation in each
subunit. The aglycon orientation, although probably determined by
packing of tetramers in the crystal lattice, helps to characterize the
orientation of the saccharide in the sugar-binding pocket. The structure
is the best determined alpha-D-glucoside:Con A complex to date and the
hydrogen bonding network in the saccharide-binding site can be described
with some confidence and compared with that of the alpha-D-mannosides.
(C) 1997 Academic Press.
Συγγραφείς:
Hamodrakas, SJ
Kanellopoulos, PN
Pavlou, K
Tucker, PA
