Secondary structure and thermal stability of the extrinsic 23 kDa protein of photosystem II studied by Fourier transform infrared spectroscopy.
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.
Zhang
H
H
Groupe de Recherche en Energie et Information Biomoléculaires, Université du Québec à Trois-Rivières, Canada.
Ishikawa
Y
Y
Yamamoto
Y
Y
Carpentier
R
R
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
D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D012996:Solutions