title: Kinetic nature of the thermal destabilization of LHCII macroaggregates.
abstract: The main light-harvesting chl a/b pigment-protein complex of photosystem II (LHCII) in isolated state forms macroaggregates with different ultrastructure and lipid content [I. Simidjiev, V. Barzda, L. Mustardy, G. Garab, Anal. Biochem. 250 (1997) 169-175]. The thermodynamic stability of highly delipidated tightly bound LHCII macroaggregates is studied by differential scanning calorimetry and fluorescence spectroscopy. The calorimetric profile of LHCII is asymmetric, the denaturation transition is taking place at around 72 degrees C. A shoulder, which overlaps with the main denaturation transition, appears around 58 degrees C. The denaturation temperature strongly depends on the scanning rate indicating the kinetic nature of the thermal destabilization of LHCII macroaggregates. The fluorescence data prove that the thermal denaturation of LHCII is an irreversible and kinetically controlled process.
authors.affiliation: Institute of Biophysics, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, Bl. 21, 1113 Sofia, Bulgaria.
authors.forename: Sashka B
authors.initials: SB
authors.lastname: Krumova
authors.forename: Svetla J
authors.initials: SJ
authors.lastname: Todinova
authors.forename: Mira C
authors.initials: MC
authors.lastname: Busheva
authors.forename: Stefka G
authors.initials: SG
authors.lastname: Taneva
mesh_terms: D002152:Calorimetry, Differential Scanning; D004795:Enzyme Stability; D007700:Kinetics; D018532:Pisum sativum / Q000201:enzymology; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D011489:Protein Denaturation; D013050:Spectrometry, Fluorescence; D018724:Spinacia oleracea / Q000201:enzymology; D013696:Temperature
chemical_list: D045332:Photosystem II Protein Complex