HeLp, a heme-transporting lipoprotein with an antioxidant role

• Published in: Insect biochemistry and molecular biology 2004, Vol.34 (1), p.81-87
• Main Authors: Maya-Monteiro, Clarissa M, Alves, Liliane R, Pinhal, Nelson, Abdalla, Dulcineia S.P, Oliveira, Pedro L
• Format: Article
• Language: English
• Subjects: Animals; Antioxidant; Antioxidants - metabolism; Antioxidants - pharmacology; Boophilus microplus; Butylated Hydroxytoluene - pharmacology; Carrier Proteins - metabolism; Carrier Proteins - pharmacology; Dose-Response Relationship, Drug; Electron Spin Resonance Spectroscopy; Free Radicals - metabolism; Heme; Heme - metabolism; Hemolymph - chemistry; Hemolysis - drug effects; Ixodidae; Lipid Metabolism; Lipid Peroxidation - drug effects; Lipids - chemistry; Lipoprotein; Lipoproteins - metabolism; Lipoproteins - pharmacology; Liposomes - metabolism; Oxidative stress; Oxygen Consumption - drug effects; Peroxidase - metabolism; Tick; Ticks - metabolism
• ISSN: 0965-1748; 1879-0240
• DOI: 10.1016/j.ibmb.2003.09.005

Plasma lipoproteins involved in lipid transport are a target for free radical-evoked pathological conditions in several mammalian models. The main hemolymphatic protein of Boophilus microplus is a heme-binding lipoprotein (HeLp, for Heme LipoProtein) that carries dietary heme produced from degradation of vertebrate hemoglobin to tissues of the tick. Addition of heme to phospholipid liposomes resulted in intense lipid peroxidation, which was inhibited by addition of HeLp. HeLp prevented lysis of red blood cells by heme. HeLp also inhibited reactions of heme with tert-butyl hydroperoxide (t-BOOH) or hydrogen peroxide. HeLp, quite differently from other lipoproteins, presents a protective intrinsic mechanism to counteract heme toxicity, while preserving the heme molecule to be reused by the tick. This is the first report of a lipoprotein acting as an antioxidant particle against heme-induced radical damage.