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Oxidized Rubredoxin Models. II. Iron(III) Complexes of Z-Cys-Pro-Leu-Cys-OMe and Z-Cys-Thr-Val-Cys-OMe

1983; Oxford University Press; Volume: 56; Issue: 12 Linguagem: Inglês

10.1246/bcsj.56.3647

1348-0634

Michio Nakata, Norikazu Ueyama, Toshitsugu Terakawa, Akira Nakamura,

Electron Spin Resonance Studies

Fe(III) complexes of cysteine-containing peptides such as Z–Cys–Pro–Leu–Cys–OMe and Z–Cys–Thr–Val–Cys–OMe corresponding to the Fe binding amino acid sequences in Cl. pasteurianum rubredoxin were prepared in solution and characterized by the absorption, circular dichroism (CD), and magnetic circular dichroism (MCD) spectra and were compared with those of the Fe(III) complexes of Z–Cys–Ala–Ala–Cys–OMe, Z–Ala–Cys–OMe, and Z–Cys–Ala–Cys–OMe. These model compelxes exhibited the existence of an electronic configuration and a core structure similar to that of native rubredoxin. The thermal stabilities of the Fe(III) pep tide complexes decrease in the following order, Z–Cys–Thr–Val–Cys–OMe>Z–Cys–Ala–Ala–Cys–OMe>Z–Cys–Pro–Leu–Cys–OMe\simeqZ–Ala–Cys–OMe>>Z–Cys–Ala–Cys–OMe.