1AMS

X-RAY CRYSTALLOGRAPHIC STUDY OF PYRIDOXAMINE 5'-PHOSPHATE-TYPE ASPARTATE AMINOTRANSFERASES FROM ESCHERICHIA COLI IN THREE FORMS

1AMS の概要

• エントリーDOI: 10.2210/pdb1ams/pdb
• 分子名称: ASPARTATE AMINOTRANSFERASE, 4'-DEOXY-4'-AMINOPYRIDOXAL-5'-PHOSPHATE, GLUTARIC ACID (3 entities in total)
• 機能のキーワード: transferase(aminotransferase)
• 由来する生物種: Escherichia coli
• 細胞内の位置: Cytoplasm: P00509
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 43999.50

構造登録者

Miyahara, I.,Hirotsu, K.,Hayashi, H.,Kagamiyama, H. (登録日: 1994-07-01, 公開日: 1994-09-30, 最終更新日: 2024-02-07)

主引用文献

Miyahara, I.,Hirotsu, K.,Hayashi, H.,Kagamiyama, H.
X-ray crystallographic study of pyridoxamine 5'-phosphate-type aspartate aminotransferases from Escherichia coli in three forms.
J.Biochem.(Tokyo), 116:1001-1012, 1994

PubMed Abstract: The three-dimensional structures of pyridoxamine 5'-phosphate-type aspartate aminotransferase from Escherichia coli and its complexes with maleate and glutarate have been determined by X-ray crystallography at 2.2, 2.1, and 2.7 A resolution, respectively. The enzyme is a dimeric form comprising two identical subunits, each of which is divided into one large and one small domain. The complex with maleate showed that substrate (or inhibitor) binding induced a large conformational change from the "open" to the "closed" form, resulting in closure of the active site by the small domain movement, as was observed in the pyridoxal 5'-phosphate-type enzyme. In the open form, three hydrophobic residues (hydrophobic plug) at the entrance of the active site are exposed to solvent. Maleate binding make the active site more hydrophobic by charge compensation and release of water molecules, facilitating the movement of the hydrophobic plug into the active site pocket to induce a large conformational change in the enzyme. Maleate is fixed rigidly in the active site pocket by extensive salt bridges and a hydrogen bonding network, guaranteeing the stereo-specificity of the catalysis and giving a Michaelis complex model. Contrary to our expectation, the glutarate complex was in the open form, suggesting that the equilibrium between the open and closed forms lies far toward the open form in solution. The water molecules located in the active site pocket were almost completely conserved between Escherichia coli and chicken mitochondrial aspartate aminotransferase with the same type of cofactor and the same conformation.

PubMed: 7896726

実験手法

X-RAY DIFFRACTION (2.7 Å)