title: Factor J, an inhibitor of the classical and alternative complement pathway, does not inhibit esterolysis by factor D.
abstract: Factor J (FJ) is an inhibitor of the classical and alternative complement pathways. On the classical pathway factor J disrupts the C1 component, and on the alternative pathway, factor J disrupts the C3 convertase (C3b,Bb) by a direct interaction of FJ with the components C3b and Bb. The aim of this work was to verify whether FJ could have any effect on factor D proteolytic activity since previous experiments could not rule out an eventual inhibition by factor J on factor D enzymatic activity. For this purpose, the reactivity of serine proteinase factor D was determined by using two peptide thioester substrates, Z-Lys-SBzl.HCl and Z-Lys-Arg-SBzl.2HCl, in the presence and in the absence of factor J. Kinetic studies evidenced that FJ did not affect the enzymatic activity of factor D in any case.
authors.affiliation: Unidad de Inmunología, Hospital La Paz, Madrid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: González-Rubio
authors.forename: R
authors.initials: R
authors.lastname: González-Muñiz
authors.forename: M A
authors.initials: MA
authors.lastname: Jiménez-Clavero
authors.forename: G
authors.initials: G
authors.lastname: Fontán
authors.forename: M
authors.initials: M
authors.lastname: López-Trascasa
mesh_terms: D003174:Complement C1 Inactivator Proteins / Q000494:pharmacology*; D050577:Complement C3-C5 Convertases / Q000037:antagonists & inhibitors; D011416:Complement Factor D / Q000037:antagonists & inhibitors* / Q000378:metabolism; D003170:Complement Pathway, Alternative / Q000187:drug effects*; D003171:Complement Pathway, Classical / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004952:Esters / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics
chemical_list: D003174:Complement C1 Inactivator Proteins; D004791:Enzyme Inhibitors; D004952:Esters; D050577:Complement C3-C5 Convertases; C493488:CFD protein, human; D011416:Complement Factor D