8EKO

Sperm whale myoglobin mutant L29H F33W F43H (F33W CuBMb)

8EKO の概要

• エントリーDOI: 10.2210/pdb8eko/pdb
• 分子名称: Myoglobin, PROTOPORPHYRIN IX CONTAINING FE (3 entities in total)
• 機能のキーワード: oxygen reduction reaction, heme-copper oxidase, biosynthetic model, oxidoreductase
• 由来する生物種: Physeter catodon (sperm whale)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 17906.44

構造登録者

Ledray, A.P.,Dwaraknath, S.,Lu, Y. (登録日: 2022-09-21, 公開日: 2022-10-26, 最終更新日: 2023-10-25)

主引用文献

Ledray, A.P.,Dwaraknath, S.,Chakarawet, K.,Sponholtz, M.R.,Merchen, C.,Van Stappen, C.,Rao, G.,Britt, R.D.,Lu, Y.
Tryptophan Can Promote Oxygen Reduction to Water in a Biosynthetic Model of Heme Copper Oxidases.
Biochemistry, 62:388-395, 2023

PubMed Abstract: Heme-copper oxidases (HCOs) utilize tyrosine (Tyr) to donate one of the four electrons required for the reduction of O to water in biological respiration, while tryptophan (Trp) is speculated to fulfill the same role in cyt oxidases. We previously engineered myoglobin into a biosynthetic model of HCOs and demonstrated the critical role that Tyr serves in the oxygen reduction reaction (ORR). To address the roles of Tyr and Trp in these oxidases, we herein report the preparation of the same biosynthetic model with the Tyr replaced by Trp and further demonstrate that Trp can also promote the ORR, albeit with lower activity. An X-ray crystal structure of the Trp variant shows a hydrogen-bonding network involving two water molecules that are organized by Trp, similar to that in the Tyr variant, which is absent in the crystal structure with the native Phe residue. Additional electron paramagnetic resonance measurements are consistent with the formation of a Trp radical species upon reacting with HO. We attribute the lower activity of the Trp variant to Trp's higher reduction potential relative to Tyr. Together, these findings demonstrate, for the first time, that Trp can indeed promote the ORR and provides a structural basis for the observation of varying activities. The results support a redox role for the conserved Trp in oxidase while suggesting that HCOs use Tyr instead of Trp to achieve higher reactivity.

PubMed: 36215733
DOI: 10.1021/acs.biochem.2c00300

実験手法

X-RAY DIFFRACTION (1.34 Å)