title: Ceruloplasmin and myeloperoxidase in complex affect the enzymatic properties of each other.
abstract: Ceruloplasmin (CP), the multicopper oxidase of plasma, interacts with myeloperoxidase (MPO), an enzyme of leukocytes, and inhibits its peroxidase and chlorinating activity. Studies on the enzymatic properties shows that CP behaves as a competitive inhibitor impeding the binding of aromatic substrates to the active centre of MPO. The contact between CP and MPO probably entails conformational changes close to the p-phenylenediamine binding site in CP, which explains the observed activation by MPO of the substrate's oxidation. CP subjected to partial proteolysis was virtually unable to inhibit activity of MPO. The possible protein-protein interface is comprised of the area near active site of MPO and the loop linking domains 5 and 6 in CP. One of the outcomes of this study is the finding of a new link between antioxidant properties of CP and its susceptibility to proteolysis.
authors.affiliation: Department of Molecular Genetics of the Institute for Experimental Medicine of the Russian Academy of Medical Sciences, Saint-Petersburg, Russia. biochem@nm.ru
authors.forename: Alexej V
authors.initials: AV
authors.lastname: Sokolov
authors.forename: Kira V
authors.initials: KV
authors.lastname: Ageeva
authors.forename: Maria O
authors.initials: MO
authors.lastname: Pulina
authors.forename: Olga S
authors.initials: OS
authors.lastname: Cherkalina
authors.forename: Valeria R
authors.initials: VR
authors.lastname: Samygina
authors.forename: Irina I
authors.initials: II
authors.lastname: Vlasova
authors.forename: Oleg M
authors.initials: OM
authors.lastname: Panasenko
authors.forename: Elena T
authors.initials: ET
authors.lastname: Zakharova
authors.forename: Vadim B
authors.initials: VB
authors.lastname: Vasilyev
mesh_terms: D002384:Catalysis; D002570:Ceruloplasmin / Q000378:metabolism*; D002713:Chlorine / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D006868:Hydrolysis; D007962:Leukocytes / Q000201:enzymology; D010088:Oxidoreductases / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism; D013053:Spectrophotometry
chemical_list: D002713:Chlorine; D010088:Oxidoreductases; D009195:Peroxidase; D002570:Ceruloplasmin; D012697:Serine Endopeptidases