4JAC

Dehaloperoxidase-Hemoglobin T56S

4JAC の概要

• エントリーDOI: 10.2210/pdb4jac/pdb
• 分子名称: Dehaloperoxidase A, PROTOPORPHYRIN IX CONTAINING FE, SULFATE ION, ... (5 entities in total)
• 機能のキーワード: peroxidase, oxidoreductase
• 由来する生物種: Amphitrite ornata
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 32924.71

構造登録者

Franzen, S.,Swartz, P.D. (登録日: 2013-02-18, 公開日: 2013-11-27, 最終更新日: 2024-02-28)

主引用文献

Jiang, S.,Wright, I.,Swartz, P.,Franzen, S.
The role of T56 in controlling the flexibility of the distal histidine in dehaloperoxidase-hemoglobin from Amphitrite ornata.
Biochim.Biophys.Acta, 1834:2020-2029, 2013

PubMed Abstract: The activation of dehaloperoxidase-hemoglobin (DHP) to form a ferryl intermediate requires the distal histidine, H55, to act as an acid base catalyst. The lack of ancillary amino acids in the distal pocket to assist in this process makes H55 even more important to the formation of active intermediates than in conventional peroxidases. Therefore, one can infer that the precise conformation H55 may greatly affect the enzymatic activity. Using site-direct mutagenesis at position T56, immediately adjacent to H55, we have confirmed that subtle changes in the conformation of H55 affect the catalytic efficiency of DHP. Mutating T56 to a smaller amino acid appears to permit H55 to rotate with relatively low barriers between conformations in the distal pocket, which may lead to an increase in catalytic activity. On the other hand, larger amino acids in the neighboring site appear to restrict the rotation of H55 due to the steric hindrance. In the case of T56V, which is an isosteric mutation, H55 appears less mobile, but forced to be closer to the heme iron than in wild type. Both proximity to the heme iron and flexibility of motion in some of the mutants can result in an increased catalytic rate, but can also lead to protein inactivation due to ligation of H55 to the heme iron, which is known as hemichrome formation. A balance of enzymatic rate and protein stability with respect to hemichrome formation appears to be optimum in wild type DHP (WT-DHP).

PubMed: 23792762
DOI: 10.1016/j.bbapap.2013.06.005

実験手法

X-RAY DIFFRACTION (1.934 Å)