title: Identification of plasma haptoglobin forms which loosely bind hemoglobin.
abstract: Haptoglobin (Hpt) is known to capture circulating free hemoglobin (Hb) and bind apolipoprotein (Apo) A-I or E. Here, we report that Hb can be tightly bound by most of Hpt molecules (TB-Hpt, 80%), whereas loosely bound by a minor part of them (LB-Hpt, 20%). LB-Hpt amount was significantly increased (over 60%) in patients with acute coronary syndrome. LB-Hpt bound ApoA-I and ApoE less efficiently than TB-Hpt (8- and 4-fold less, respectively) and did not affect their activity of stimulating the enzyme lecithin-cholesterol acyltransferase. LB-Hpt and TB-Hpt displayed comparable levels of nitrotyrosine residues, but differences in glycan chains. Changes in LB-Hpt level might be associated with changes in Hpt functions.
authors.affiliation: Istituto per il Sistema Produzione Animale in Ambiente Mediterraneo, Consiglio Nazionale delle Ricerche, Naples, Italy.
authors.forename: Maria Stefania
authors.initials: MS
authors.lastname: Spagnuolo
authors.forename: Luisa
authors.initials: L
authors.lastname: Cigliano
authors.forename: Bernardetta
authors.initials: B
authors.lastname: Maresca
authors.forename: Carmela Regina
authors.initials: CR
authors.lastname: Pugliese
authors.forename: Paolo
authors.initials: P
authors.lastname: Abrescia
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood / Q000201:enzymology; D016632:Apolipoprotein A-I / Q000378:metabolism; D001057:Apolipoproteins E / Q000378:metabolism; D016022:Case-Control Studies; D006242:Haptoglobins / Q000378:metabolism* / Q000494:pharmacology; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D037102:Lectins / Q000378:metabolism; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000378:metabolism; D011485:Protein Binding
chemical_list: D016632:Apolipoprotein A-I; D001057:Apolipoproteins E; D006242:Haptoglobins; D006454:Hemoglobins; D037102:Lectins; D007862:Phosphatidylcholine-Sterol O-Acyltransferase