The crystal structure of the complex of concanavalin A with 4'-methylumbelliferyl-alpha-D-glucopyranoside.
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 A, b = 128.71 A, c = 82.23 A, and beta = 118.47 degrees. X-ray diffraction intensities to 2.78 A have been collected. The structure of the complex was solved by molecular replacement and 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.
Hamodrakas
S J
SJ
Department of Biology, Section of Cell Biology and Biophysics, University of Athens, Panepistimiopolis, Greece.
Kanellopoulos
P N
PN
Pavlou
K
K
Tucker
P A
PA
D001665:Binding Sites; D003208:Concanavalin A / Q000378:metabolism / Q000648:ultrastructure*; D018360:Crystallography, X-Ray; D006923:Hymecromone / Q000031:analogs & derivatives* / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation
D003208:Concanavalin A; D006923:Hymecromone; C034888:4-methylumbelliferyl glucuronide