1PP2

THE REFINED CRYSTAL STRUCTURE OF DIMERIC PHOSPHOLIPASE A2 AT 2.5 ANGSTROMS. ACCESS TO A SHIELDED CATALYTIC CENTER

1PP2 の概要

• エントリーDOI: 10.2210/pdb1pp2/pdb
• 分子名称: CALCIUM-FREE PHOSPHOLIPASE A2 (2 entities in total)
• 機能のキーワード: hydrolase
• 由来する生物種: Crotalus atrox (western diamondback rattlesnake)
• 細胞内の位置: Secreted: P00624
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 27214.55

構造登録者

Brunie, S.,Sigler, P.B. (登録日: 1986-03-10, 公開日: 1986-05-07, 最終更新日: 2024-11-13)

主引用文献

Brunie, S.,Bolin, J.,Gewirth, D.,Sigler, P.B.
The refined crystal structure of dimeric phospholipase A2 at 2.5 A. Access to a shielded catalytic center.
J.Biol.Chem., 260:9742-9749, 1985

PubMed Abstract: The 2.5-A crystal structure of the calcium-free form of the dimeric venom phospholipase A2 from the Western Diamondback rattlesnake Crotalus atrox, has been refined to an R-factor of 17.8% (I greater than 2 sigma) and acceptable stereochemistry. The molecule is a nearly perfect 2-fold symmetric dimer in which most of the catalytic residues of both subunits face an internal cavity. The restricted access to the putative catalytic sites is especially puzzling as the optimal substrates for this and most other phospholipase A2 are phospholipids condensed in micellar or lamellar aggregates. We point out that substrate access to the internal cavity may be aided by calcium binding which can alter the intersubunit contacts that shield the catalytic network. We also suggest that a system of hydrogen-bonded moieties exists on the surface of the dimer that links the amino terminus to the catalytic system, through an invariant Gln 4 side chain and the backbone of the active center residue, Tyr 73. This hydrogen-bonded network is on a highly accessible surface of the dimer and would appear to contribute to the enzyme's (as opposed to the proenzyme's) special capacity to attack aggregated rather than monomeric substrate.

PubMed: 4019493

実験手法

X-RAY DIFFRACTION (2.5 Å)