title: Secondary structure and thermostability of the photosystem II manganese-stabilizing protein of the thermophilic cyanobacterium Synechococcus elongatus.
abstract: The secondary structure of the manganese-stabilizing protein of the thermophilic cyanobacterium Synechococcus elongatus in solution was investigated by Fourier-transform infrared (FT-IR) and circular dichroism (CD) spectroscopies. Both methods showed a high proportion of disordered structure (40-43%) and a relatively small amount of beta-sheet (23-24%) and alpha-helix (17-19%). The conformation of the protein remained essentially unchanged at temperatures up to 70 degrees C. Unfolding of the protein occurred at higher temperatures and FT-IR spectroscopy revealed that beta-sheet was more strongly unfolded than alpha-helix at 76 degrees C. The protein largely lost the ordered secondary structures at 90 degrees C, but, when cooled down to 30 degrees C, regained its original conformation. Thus, the cyanobacterial protein is very thermostable and its denaturation at an extremely high temperature is reversible.
authors.affiliation: Material Science Laboratory, Toray Research Center, Inc., Otsu, Japan. sonoyamam@vxoal.scc.toray.co.jp
authors.forename: M
authors.initials: M
authors.lastname: Sonoyama
authors.forename: A
authors.initials: A
authors.lastname: Motoki
authors.forename: G
authors.initials: G
authors.lastname: Okamoto
authors.forename: M
authors.initials: M
authors.lastname: Hirano
authors.forename: H
authors.initials: H
authors.lastname: Ishida
authors.forename: S
authors.initials: S
authors.lastname: Katoh
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D002942:Circular Dichroism; D000458:Cyanobacteria / Q000737:chemistry*; D004795:Enzyme Stability; D008345:Manganese / Q000494:pharmacology*; D008667:Metalloproteins / Q000737:chemistry; D045332:Photosystem II Protein Complex; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D008667:Metalloproteins; D045332:Photosystem II Protein Complex; D011506:Proteins; C054266:photosystem II manganese-stabilizing protein; D008345:Manganese