Photodynamic action of merocyanine 540 on erythrocyte membranes: structural perturbation of lipid and protein constituents. Biochim Biophys Acta 1991 Sep 02;1075(1):28-35
Date
09/02/1991Pubmed ID
1654108DOI
10.1016/0304-4165(91)90070-wScopus ID
2-s2.0-0025851424 (requires institutional sign-in at Scopus site) 56 CitationsAbstract
erocyanine 540 (MC540) is a membrane-directed photosensitizing dye with antileukemic and antiviral properties. In this study, biophysical and biochemical techniques have been used to examine MC540-sensitized photooxidative damage in the lipid and protein compartments of a test membrane, the human erythrocyte ghost. Irradiation of MC540-sensitized ghosts with white light resulted in oxidative damage to proteins, as manifested by (i) loss of sulfhydryl groups; (ii) intermolecular cross-linking of major polypeptides; and (iii) loss of Mg(2+)-ATPase and Na+,K(+)-ATPase activities. Photooxidation also produced a rapid and progressive increase in general protein motion, as measured by electron paramagnetic resonance spectrometry (EPR) with the sulfhydryl spin label MAL-6. In addition to these effects, ghosts exposed to MC540 and light underwent lipid peroxidation. EPR with two lipophilic spin probes, 5-doxylstearate and 16-doxylstearate, showed that lipid peroxidation is accompanied by a progressive decrease in bilayer fluidity (motional freedom). At a given dye concentration, structural perturbations of proteins were detected at much lower light fluences than those of lipids. When photoreactions were carried out in the presence of ascorbate and iron, there was a strong stimulation of lipid peroxidation (attributed to free radical chain reactions), with a concomitant greater decrease in lipid mobility. Thus, the deleterious effects of photoperoxidation on lipid structure and motional freedom were greatly exacerbated by ascorbate and iron. Membrane damage similar to that described here may play a role in the phototherapeutic activity of MC540.
Author List
Feix JB, Bachowski GJ, Girotti AWAuthors
Jimmy B. Feix PhD Professor in the Biophysics department at Medical College of WisconsinAlbert W. Girotti PhD Adjunct Professor in the Biochemistry department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
Adenosine TriphosphatasesElectron Spin Resonance Spectroscopy
Electrophoresis, Polyacrylamide Gel
Erythrocyte Membrane
Humans
Lipid Bilayers
Lipid Peroxidation
Membrane Fluidity
Membrane Lipids
Membrane Proteins
Photochemistry
Pyrimidinones
Radiation-Sensitizing Agents
Sulfhydryl Compounds
