title: The effects of Na+ and Mg2+ on the thermal denaturation of native and acetylated spinach ferredoxins.
abstract: The effects of metal ions on the thermal denaturation and Mg2+ binding of native spinach ferredoxin and its acetylated derivative were investigated. The denaturation of ferredoxin in a metal-free solution at 40 degrees C was quickly prevented by the addition of Mg2+ or Na+ at appropriate concentrations. The metal concentrations required for 50% protection from thermal denaturation were 1.54 x 10(-4) M Mg2+ or 8.0 x 10(-3) M Na+ for native ferredoxin and 1.05 x 10(-3) M Mg2+ or 6.0 x 10(-2) M Na+ for acetylated ferredoxin. It was also found that native ferredoxin in the presence of over 20 mM Mg2+ was almost completely protected from thermal denaturation at 40 degrees C. The D-form which has been observed in acetylated ferredoxin by Masaki et al. (1977) (J. Biochem. 81, 1-9) was confirmed to be present in native ferredoxin at high temperature (49 degrees C) and is suggested to be an important form in the denaturation processes of the ferredoxin molecule.
mesh_terms: D000107:Acetylation; D005288:Ferredoxins; D006358:Hot Temperature; D007700:Kinetics; D008274:Magnesium; D010944:Plants / Q000032:analysis*; D011485:Protein Binding; D011489:Protein Denaturation; D012964:Sodium; D013053:Spectrophotometry
chemical_list: D005288:Ferredoxins; D012964:Sodium; D008274:Magnesium