A Study of Ligand Binding to Spleen Myeloperoxidase

Masao Ikeda-Saito

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

The ligand binding properties of spleen myeloperoxidase, a peroxidase formerly called “the spleen green hemeprotein”, were studied as functions of temperature and pH, using chloride and cyanide as exogenous ligands. Ligand binding is influenced by a proton dissociable group with a pKaof 4. The protonated, uncharged form of cyanide binds to the unprotonated form of the enzyme, while chloride ion binds to the enzyme when this group is protonated. In both cyanide and chloride binding, the pH-dependent change in the apparent ligand affinity is due to a change in the apparent association rate with pH. The proton dissociable group on the enzyme involved in ligand binding has a AH value of about 8 kcal-mol-1. The present results suggest that this ionizable group is the imidazole group of a histidine residue located near the ligand binding site.

Original languageEnglish
Pages (from-to)4344-4349
Number of pages6
JournalBiochemistry
Volume26
Issue number14
DOIs
Publication statusPublished - 1987 Jan 1

ASJC Scopus subject areas

  • Biochemistry

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