1AI3

ORBITAL STEERING IN THE CATALYTIC POWER OF ENZYMES: SMALL STRUCTURAL CHANGES WITH LARGE CATALYTIC CONSEQUENCES

1AI3 の概要

• エントリーDOI: 10.2210/pdb1ai3/pdb
• 分子名称: ISOCITRATE DEHYDROGENASE, NICOTINAMIDE-(6-DEAMINO-6-HYDROXY-ADENINE)-DINUCLEOTIDE PHOSPHATE, ISOCITRIC ACID, ... (5 entities in total)
• 機能のキーワード: oxidoreductase (nad(a)-choh(d)), nadp, phosphorylation, glyoxylate bypass, oxidoreductase
• 由来する生物種: Escherichia coli
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 46770.38

構造登録者

Stoddard, B.L.,Mesecar, A.,Koshland Junior, D.E. (登録日: 1997-04-30, 公開日: 1997-11-12, 最終更新日: 2024-12-25)

主引用文献

Mesecar, A.D.,Stoddard, B.L.,Koshland Jr., D.E.
Orbital steering in the catalytic power of enzymes: small structural changes with large catalytic consequences.
Science, 277:202-206, 1997

PubMed Abstract: Small structural perturbations in the enzyme isocitrate dehydrogenase (IDH) were made in order to evaluate the contribution of precise substrate alignment to the catalytic power of an enzyme. The reaction trajectory of IDH was modified (i) after the adenine moiety of nicotinamide adenine dinucleotide phosphate was changed to hypoxanthine (the 6-amino was changed to 6-hydroxyl), and (ii) by replacing Mg2+, which has six coordinating ligands, with Ca2+, which has eight coordinating ligands. Both changes make large (10(-3) to 10(-5)) changes in the reaction velocity but only small changes in the orientation of the substrates (both distance and angle) as revealed by cryocrystallographic trapping of active IDH complexes. The results provide evidence that orbital overlap produced by optimal orientation of reacting orbitals plays a major quantitative role in the catalytic power of enzymes.

PubMed: 9211842
DOI: 10.1126/science.277.5323.202

実験手法

X-RAY DIFFRACTION (1.9 Å)