Pentacoordination of the heme iron of Arthromyces ramosus peroxidase shown by a 1.8 Å resolution crystallographic study at pH 4.5

FEBS Letters

Amada, Fumiko¹  Kawamoto, Masahide¹  Matsunaga, Takateru¹  Matsubara, Hiroshi¹  Kunishima, Naoki¹  Fukuyama, Keiichi¹ 

[1] Department of Biology, Faculty of Science, Osaka University, Toyonaka, Osaka 560, Japan

关键词: Peroxidase;    Heme enzyme;    Coordination of heme;    X-ray crystallography;    Athromyces ramosus;    ARP;    Arthromyces ramosus peroxidase;    HRP;    horseradish peroxidase;    LiP;    lignin peroxidase;    CcP;    cytochrome c peroxidase;    MnP;    manganese peroxidase;    IP;    imaging plate;   

DOI  :  10.1016/0014-5793(95)01458-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In the presence of ammonium sulfate the absorption spectra of a peroxidase from the fungus Arthromyces ramosus (ARP) showed that the low-spin component increased as the pH increased from 6.0 to 9.0, whereas in its absence ARP remained in the high-spin state in the pH range investigated. The crystal structure of ARP at pH 4.5 in the presence of ammonium sulfate at 1.8 Å resolution showed that the electron density at the 6th position of the heme iron seen at pH 7.5 had disappeared and that the iron atom deviated markedly from the heme plane. These observations strongly suggest that under physiological conditions the heme of ARP is in the pentacoordinated high-spin state and that at a high pH the heme iron is able to bind ammonia, forming the low-spin state. The location of the water molecule at the distal side of the heme in peroxidases is also discussed.

【 授权许可】

Unknown