title: Secondary structure and thermal stability of the extrinsic 23 kDa protein of photosystem II studied by Fourier transform infrared spectroscopy.
abstract: The secondary structure and thermal stability of the extrinsic 23 kDa protein (OEC23) of spinach photosystem II have been characterized in solution between 25 and 75 degrees C using Fourier transform infrared spectroscopy. Quantitative analysis of the amide I band (1700-1600 cm(-1)) shows that OEC23 contains 5% alpha-helix, 37% beta-sheet, 24% turn, and 34% disorder structures at 25 degrees C. No appreciable conformational changes occur below 45 degrees C. At elevated temperatures, the beta-sheet structure is unfolded into the disorder structure with a major conformational transition occurring at 55 degrees C. Implications of these results for the functions of OEC23 in photosystem II are discussed.
authors.affiliation: Groupe de Recherche en Energie et Information Biomoléculaires, Université du Québec à Trois-Rivières, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: Y
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: R
authors.initials: R
authors.lastname: Carpentier
mesh_terms: D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000302:isolation & purification; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D017433:Protein Structure, Secondary; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D018724:Spinacia oleracea; D013696:Temperature
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D012996:Solutions