1J4B

Recombinant Mouse-Muscle Adenylosuccinate Synthetase

1J4B の概要

• エントリーDOI: 10.2210/pdb1j4b/pdb
• 分子名称: adenylosuccinate synthetase (2 entities in total)
• 機能のキーワード: ligase, gtp-hydrolyzing enzymes, purine nucleotide cycle
• 由来する生物種: Mus musculus (house mouse)
• 細胞内の位置: Cytoplasm: P28650
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 50321.30

構造登録者

Iancu, C.V.,Borza, T.,Choe, J.Y.,Fromm, H.J.,Honzatko, R.B. (登録日: 2001-09-07, 公開日: 2001-11-21, 最終更新日: 2023-08-16)

主引用文献

Iancu, C.V.,Borza, T.,Choe, J.Y.,Fromm, H.J.,Honzatko, R.B.
Recombinant mouse muscle adenylosuccinate synthetase: overexpression, kinetics, and crystal structure.
J.Biol.Chem., 276:42146-42152, 2001

PubMed Abstract: Vertebrates possess two isozymes of adenylosuccinate synthetase. The acidic isozyme is similar to the synthetase from bacteria and plants, being involved in the de novo biosynthesis of AMP, whereas the basic isozyme participates in the purine nucleotide cycle. Reported here is the first instance of overexpression and crystal structure determination of a basic isozyme of adenylosuccinate synthetase. The recombinant mouse muscle enzyme purified to homogeneity in milligram quantities exhibits a specific activity comparable with that of the rat muscle enzyme isolated from tissue and K(m) parameters for GTP, IMP, and l-aspartate (12, 45, and 140 microm, respectively) similar to those of the enzyme from Escherichia coli. The mouse muscle and E. coli enzymes have similar polypeptide folds, differing primarily in the conformation of loops, involved in substrate recognition and stabilization of the transition state. Residues 65-68 of the muscle isozyme adopt a conformation not observed in any previous synthetase structure. In its new conformation, segment 65-68 forms intramolecular hydrogen bonds with residues essential for the recognition of IMP and, in fact, sterically excludes IMP from the active site. Observed differences in ligand recognition among adenylosuccinate synthetases may be due in part to conformational variations in the IMP pocket of the ligand-free enzymes.

PubMed: 11560929
DOI: 10.1074/jbc.M106294200

実験手法

X-RAY DIFFRACTION (2.5 Å)