1RPX

D-RIBULOSE-5-PHOSPHATE 3-EPIMERASE FROM SOLANUM TUBEROSUM CHLOROPLASTS

1RPX の概要

• エントリーDOI: 10.2210/pdb1rpx/pdb
• 分子名称: PROTEIN (RIBULOSE-PHOSPHATE 3-EPIMERASE), SULFATE ION (3 entities in total)
• 機能のキーワード: 3-epimerase, chloroplast, calvin cycle, oxidative pentose phosphate pathway
• 由来する生物種: Solanum tuberosum (potato)
• 細胞内の位置: Plastid, chloroplast thylakoid membrane: Q43843
• タンパク質・核酸の鎖数: 3
• 化学式量合計: 74221.28

構造登録者

Kopp, J.,Schulz, G.E. (登録日: 1998-12-01, 公開日: 1999-04-07, 最終更新日: 2023-12-27)

主引用文献

Kopp, J.,Kopriva, S.,Suss, K.H.,Schulz, G.E.
Structure and mechanism of the amphibolic enzyme D-ribulose-5-phosphate 3-epimerase from potato chloroplasts.
J.Mol.Biol., 287:761-771, 1999

PubMed Abstract: Ribulose-5-phosphate 3-epimerase (EC 5.1.3.1) catalyzes the interconversion of ribulose-5-phosphate and xylulose-5-phosphate in the Calvin cycle and in the oxidative pentose phosphate pathway. The enzyme from potato chloroplasts was expressed in Escherichia coli, isolated and crystallized. The crystal structure was elucidated by multiple isomorphous replacement and refined at 2.3 A resolution. The enzyme is a homohexamer with D3 symmetry. The subunit chain fold is a (beta alpha)8-barrel. A sequence comparison with homologous epimerases outlined the active center and indicated that all members of this family are likely to share the same catalytic mechanism. The substrate could be modeled by putting its phosphate onto the observed sulfate position and its epimerized C3 atom between two carboxylates that participate in an extensive hydrogen bonding system. A mutation confirmed the crucial role of one of these carboxylates. The geometry together with the conservation pattern suggests that the negative charge of the putative cis-ene-diolate intermediate is stabilized by the transient induced dipoles of a methionine sulfur "cushion", which is proton-free and therefore prevents isomerization instead of epimerization.

PubMed: 10191144
DOI: 10.1006/jmbi.1999.2643

実験手法

X-RAY DIFFRACTION (2.3 Å)