Z Zhang1, J Zeng, H Yin, D Tang, D Borchman, C A Paterson. 1. Department of Ophthalmology & Visual Sciences, Kentucky Lion Eye Research Institute, University of Louisville School of Medicine, Kentucky 40292, USA.
Abstract
PURPOSE: To determine the effect of alpha-crystallin binding on lens membrane lipid characteristics and the stability of Ca2+ -ATPase activity when challenged with H2O2 or elevated temperatures. METHODS: Alpha-Crystallin binding to muscle sarcoplasmic reticulum membranes was quantified using a centrifugation protocol. Alpha-Crystallin binding to lens epithelial lipids was measured by a fluorescence energy transfer technique. Lipid phase transition temperature and lipid order was measured using fluorescence spectroscopy. Ca2+ -ATPase activity was measured using classical biochemical assays. RESULTS: The main phase transition temperatures of multilamellar vesicles composed of sphingomyelin or lipids extracted from bovine lens were 40 degrees C and 20 degrees C, respectively. In the presence of saturating amounts of alpha-crystallin, the phase transition temperature and lipid order of both sphingomyelin and lens lipid membranes remained almost the same as that without alpha-crystallin. The interaction of alpha-crystallin and lipid is likely to be restricted to the membrane surface. The binding of alpha-crystallin did not influence the oxidative or thermal inactivation of the Ca2+ -ATPase pump. CONCLUSION: Alpha-Crystallin-lens membrane binding does not protect the Ca2+ -ATPase pump from thermal derangement or oxidation by H2O2.
PURPOSE: To determine the effect of alpha-crystallin binding on lens membrane lipid characteristics and the stability of Ca2+ -ATPase activity when challenged with H2O2 or elevated temperatures. METHODS: Alpha-Crystallin binding to muscle sarcoplasmic reticulum membranes was quantified using a centrifugation protocol. Alpha-Crystallin binding to lens epithelial lipids was measured by a fluorescence energy transfer technique. Lipid phase transition temperature and lipid order was measured using fluorescence spectroscopy. Ca2+ -ATPase activity was measured using classical biochemical assays. RESULTS: The main phase transition temperatures of multilamellar vesicles composed of sphingomyelin or lipids extracted from bovine lens were 40 degrees C and 20 degrees C, respectively. In the presence of saturating amounts of alpha-crystallin, the phase transition temperature and lipid order of both sphingomyelin and lens lipid membranes remained almost the same as that without alpha-crystallin. The interaction of alpha-crystallin and lipid is likely to be restricted to the membrane surface. The binding of alpha-crystallin did not influence the oxidative or thermal inactivation of the Ca2+ -ATPase pump. CONCLUSION: Alpha-Crystallin-lens membrane binding does not protect the Ca2+ -ATPase pump from thermal derangement or oxidation by H2O2.
Authors: Jessica R Nealon; Stephen J Blanksby; Paul J Donaldson; Roger J W Truscott; Todd W Mitchell Journal: Invest Ophthalmol Vis Sci Date: 2011-02-09 Impact factor: 4.799
Authors: Z Török; P Goloubinoff; I Horváth; N M Tsvetkova; A Glatz; G Balogh; V Varvasovszki; D A Los; E Vierling; J H Crowe; L Vigh Journal: Proc Natl Acad Sci U S A Date: 2001-02-27 Impact factor: 11.205
Authors: Nelly M Tsvetkova; Ibolya Horváth; Zsolt Török; Willem F Wolkers; Zsolt Balogi; Natalia Shigapova; Lois M Crowe; Fern Tablin; Elizabeth Vierling; John H Crowe; László Vigh Journal: Proc Natl Acad Sci U S A Date: 2002-10-04 Impact factor: 11.205