XFEL Crystal Structures of Peroxidase Compound II. Issue 26 (19th May 2021)

• Record Type: Journal Article
• Authors: Kwon, Hanna; Basran, Jaswir; Pathak, Chinar; Hussain, Mahdi; Freeman, Samuel L.; Fielding, Alistair J.; Bailey, Anna J.; Stefanou, Natalia; Sparkes, Hazel A.; Tosha, Takehiko; Yamashita, Keitaro; Hirata, Kunio; Murakami, Hironori; Ueno, Go; Ago, Hideo; Tono, Kensuke; Yamamoto, Masaki; Sawai, Hitomi; Shiro, Yoshitsugu; Sugimoto, Hiroshi; Raven, Emma L.; Moody, Peter C. E.
• Is Part Of: Angewandte Chemie international edition. Volume 60:Issue 26(2021)
• Page Start: 14578
• Page End: 14585
• Publication Date: 2021-05-19
• Subjects: heme -- heme proteins -- peroxidase; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202103010
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Oxygen activation in all heme enzymes requires the formation of high oxidation states of iron, usually referred to as ferryl heme. There are two known intermediates: Compound I and Compound II. The nature of the ferryl heme—and whether it is an Fe IV =O or Fe IV ‐OH species—is important for controlling reactivity across groups of heme enzymes. The most recent evidence for Compound I indicates that the ferryl heme is an unprotonated Fe IV =O species. For Compound II, the nature of the ferryl heme is not unambiguously established. Here, we report 1.06 Å and 1.50 Å crystal structures for Compound II intermediates in cytochrome c peroxidase (C c P) and ascorbate peroxidase (APX), collected using the X‐ray free electron laser at SACLA. The structures reveal differences between the two peroxidases. The iron‐oxygen bond length in C c P (1.76 Å) is notably shorter than in APX (1.87 Å). The results indicate that the ferryl species is finely tuned across Compound I and Compound II species in closely related peroxidase enzymes. We propose that this fine‐tuning is linked to the functional need for proton delivery to the heme. Abstract : Enzymatic fine‐tuning of heme reactivity: Free‐electron laser crystal structures of two different heme‐containing peroxidases—cytochrome c peroxidase and ascorbate peroxidase—show differences in the nature of the ferryl species. Precise enzymatic fine‐tuning within structurally similar heme active sites is implicated.