1A4C

AZURIN MUTANT WITH MET 121 REPLACED BY HIS, PH 3.5 CRYSTAL FORM, DATA COLLECTED AT-180 DEGREES CELSIUS

1A4C の概要

• エントリーDOI: 10.2210/pdb1a4c/pdb
• 分子名称: AZURIN, COPPER (II) ION, SULFATE ION, ... (5 entities in total)
• 機能のキーワード: electron transport, cuproprotein
• 由来する生物種: Achromobacter denitrificans
• 細胞内の位置: Periplasm: P00280
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 56781.93

構造登録者

Messerschmidt, A.,Prade, L. (登録日: 1998-01-28, 公開日: 1998-04-29, 最終更新日: 2023-08-02)

主引用文献

Messerschmidt, A.,Prade, L.,Kroes, S.J.,Sanders-Loehr, J.,Huber, R.,Canters, G.W.
Rack-induced metal binding vs. flexibility: Met121His azurin crystal structures at different pH.
Proc.Natl.Acad.Sci.USA, 95:3443-3448, 1998

PubMed Abstract: The rack-induced bonding mechanism of metals to proteins is a useful concept for explaining the generation of metal sites in electron transfer proteins, such as the blue copper proteins, that are designed for rapid electron transfer. The trigonal pyramidal structure imposed by the protein with three strong equatorial ligands (one Cys and two His) provides a favorable geometry for both cuprous and cupric oxidation states. However, the crystal structures of the Met121His mutant of azurin from Alcaligenes denitrificans at pH 6.5 (1.89- and 1.91-A resolutions) and pH 3.5 (2.45-A resolution) show that the preformed metal binding cavity in the protein is more flexible than expected. At high pH (6.5), the Cu site retains the same three equatorial ligands as in the wild-type azurin and adds His121 as a fourth strong ligand, creating a tetrahedral copper site geometry with a green color referred to as 1.5 type. In the low pH (3.5) structure, the protonation of His121 causes a conformational change in residues 117-123, moving His121 away from the copper. The empty coordination site is occupied by an oxygen atom of a nitrate molecule of the buffer solution. This axial ligand is coordinated less strongly, generating a distorted tetrahedral copper geometry with a blue color and spectroscopic properties of a type-1 site. These crystal structures demonstrate that blue copper proteins are flexible enough to permit a range of movement of the Cu atom along the axial direction of the trigonal pyramid.

PubMed: 9520385
DOI: 10.1073/pnas.95.7.3443

実験手法

X-RAY DIFFRACTION (2.45 Å)