Crystal structure of pig pancreatic alpha-amylase isoenzyme II, in complex with the carbohydrate inhibitor acarbose.
Two different crystal forms of pig pancreatic alpha-amylase isoenzyme II (PPAII), free and complexed to a carbohydrate inhibitor (acarbose), have been compared together and to previously reported structures of PPAI. A crystal form obtained at 4 degrees C, containing nearly 72% solvent, made it possible to obtain a new complex with acarbose, different from a previous one obtained at 20 degrees C [Qian, M., Buisson, G., Duée, E., Haser, H. & Payan, F. (1994) Biochemistry 33, 6284-6294]. In the present form, six contiguous subsites of the enzyme active site are occupied by the carbohydrate ligand; the structural data indicate that the binding site is capable of holding more than the five glucose units of the scheme proposed through kinetic studies. A monosaccharide ring bridging two protein molecules related by the crystal packing is located on the surface, at a distance of 2.0 nm from the reducing end of the inhibitor ligand; the symmetry-related glucose ring in the crystal lattice is found 1.5 nm away from the non-reducing end of the inhibitor ligand.
Gilles
C
C
LCCMB-IBSM, CNRS, Marseille, France.
Astier
J P
JP
Marchis-Mouren
G
G
Cambillau
C
C
Payan
F
F
D020909:Acarbose; D000818:Animals; D001665:Binding Sites; D002240:Carbohydrate Sequence; D003460:Crystallization; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006860:Hydrogen Bonding; D007527:Isoenzymes / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010179:Pancreas / Q000201:enzymology*; D011485:Protein Binding; D013552:Swine; D013696:Temperature; D014312:Trisaccharides / Q000737:chemistry* / Q000494:pharmacology; D000516:alpha-Amylases / Q000737:chemistry* / Q000302:isolation & purification
D004791:Enzyme Inhibitors; D007527:Isoenzymes; D014312:Trisaccharides; D000516:alpha-Amylases; D005947:Glucose; D020909:Acarbose