Crystal structures of human pancreatic alpha-amylase in complex with carbohydrate and proteinaceous inhibitors.
Crystal structures of human pancreatic alpha-amylase (HPA) in complex with naturally occurring inhibitors have been solved. The tetrasaccharide acarbose and a pseudo-pentasaccharide of the trestatin family produced identical continuous electron densities corresponding to a pentasaccharide species, spanning the -3 to +2 subsites of the enzyme, presumably resulting from transglycosylation. Binding of the acarviosine core linked to a glucose residue at subsites -1 to +2 appears to be a critical part of the interaction process between alpha-amylases and trestatin-derived inhibitors. Two crystal forms, obtained at different values of pH, for the complex of HPA with the protein inhibitor from Phaseolus vulgaris (alpha-amylase inhibitor) have been solved. The flexible loop typical of the mammalian alpha-amylases was shown to exist in two different conformations, suggesting that loop closure is pH-sensitive. Structural information is provided for the important inhibitor residue, Arg-74, which has not been observed previously in structural analyses.
Nahoum
V
V
Architecture et Fonction des Macromolécules Biologiques, CNRS-IFR1, 31 Chemin Joseph Aiguier, 13402 Marseille, France.
Roux
G
G
Anton
V
V
Rougé
P
P
Puigserver
A
A
Bischoff
H
H
Henrissat
B
B
Payan
F
F
D020909:Acarbose / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D000606:Amino Sugars / Q000378:metabolism / Q000494:pharmacology; D001120:Arginine / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004583:Electrons; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D006031:Glycosylation; D006801:Humans; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D037102:Lectins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010179:Pancreas / Q000201:enzymology*; D037121:Plant Lectins; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D011487:Protein Conformation; D014312:Trisaccharides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D000516:alpha-Amylases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*
D000606:Amino Sugars; D004791:Enzyme Inhibitors; D037102:Lectins; D037121:Plant Lectins; D010940:Plant Proteins; D011134:Polysaccharides; D014312:Trisaccharides; C061510:alpha-amylase inhibitor, Phaseolus vulgaris; C076099:acarviosine; C038505:trestatin; D001120:Arginine; D000516:alpha-Amylases; D020909:Acarbose