Three-dimensional structures of aspartate aminotransferase from Escherichia coli and its mutant enzyme at 2.5 A resolution.
The structure of Escherichia coli aspartate aminotransferase complex with the inhibitor 2-methylaspartate, and that of the mutant enzyme in which an arginine was substituted for a lysine residue thereby forming a Schiff base with the coenzyme pyridoxal 5'-phosphate, were determined at 2.5 A resolution, by the molecular replacement method using the known structure of pig cytosolic aspartate aminotransferase. The enzyme catalyzes the reversible transamination between L-aspartate and alpha-ketoglutarate, and forms a dimeric structure of two identical subunits. Each subunit comprises two domains, a small and a large one. Although, in general, the overall and secondary structure of E. coli enzyme are similar to those of higher animals, some differences of enzymatic action between the enzyme from E. coli and those from higher animals could be explained on the basis of the X-ray structures and molecular mechanics calculation based on them.
Kamitori
S
S
Department of Chemistry, Faculty of Science, Osaka City University.
Okamoto
A
A
Hirotsu
K
K
Higuchi
T
T
Kuramitsu
S
S
Kagamiyama
H
H
Matsuura
Y
Y
Katsube
Y
Y
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001120:Arginine / Q000032:analysis; D001219:Aspartate Aminotransferases / Q000737:chemistry* / Q000235:genetics; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003461:Crystallography; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D007700:Kinetics; D008239:Lysine / Q000032:analysis; D009154:Mutation; D011487:Protein Conformation; D012545:Schiff Bases; D013552:Swine; D014961:X-Ray Diffraction
D000596:Amino Acids; D012545:Schiff Bases; D001120:Arginine; D001219:Aspartate Aminotransferases; D008239:Lysine