2PBG

6-PHOSPHO-BETA-D-GALACTOSIDASE FORM-B

2PBG の概要

• エントリーDOI: 10.2210/pdb2pbg/pdb
• 分子名称: 6-PHOSPHO-BETA-D-GALACTOSIDASE, SULFATE ION (3 entities in total)
• 機能のキーワード: hydrolase, glycosyl hydrolase
• 由来する生物種: Lactococcus lactis
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 54251.24

構造登録者

Wiesmann, C.,Schulz, G.E. (登録日: 1997-02-21, 公開日: 1997-07-23, 最終更新日: 2024-05-22)

主引用文献

Wiesmann, C.,Hengstenberg, W.,Schulz, G.E.
Crystal structures and mechanism of 6-phospho-beta-galactosidase from Lactococcus lactis.
J.Mol.Biol., 269:851-860, 1997

PubMed Abstract: The initial structural model of 6-phospho-beta-galactosidase from Lactococcus lactis was refined to an R-factor of 16.4% (R[free] = 23.6%) to 2.3 A resolution (1 A = 0.1 nm), and the structures of three other crystal forms were solved by molecular replacement. The four structural models are essentially identical. The catalytic center of the enzyme is approximately at the mass center of the molecule and can only be reached through a 20 A long channel, which is observed with an "open" or "closed" entrance. The closed entrance is probably too small for the educt lactose-6-phosphate to enter, but large enough for the first product glucose to leave. Among the presented structures is a complex between an almost inactive mutant and the second product galactose-6-phosphate, which is exclusively bound at side-chains. A superposition (onto the native enzyme) of galactose-6-phosphate as bound to the mutant suggests the geometry of a postulated covalent intermediate. The binding mode of the educt was modeled, starting from the bound galactose-6-phosphate. A tightly fixed tryptophan is used as a chopping-board for splitting the disaccharide, and several other aromatic residues in the active center cavity are likely to participate in substrate transport/binding.

PubMed: 9223646
DOI: 10.1006/jmbi.1997.1084

実験手法

X-RAY DIFFRACTION (2.5 Å)