Kraatz H B, Galka M
Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada.
Met Ions Biol Syst. 2001;38:385-409.
Recent studies clearly show the utility of the carbodiimide protocol to attach the redox-active Fc moiety to the N-terminal side of amino acids and peptides under mild conditions, resulting in stable and often crystalline products that afford themselves to structural analysis by X-ray crystallography. Electrochemical studies of Fc-peptides show that there is a significant influence of the redox potential depending on the amino acid sequence. The Fc moiety is sensitive to structural changes that occur in the peptide to which it is attached. For helical Fc-oligoprolines, the redox potential of the Fc group makes it easier to oxidize as the oligoproline chain increases in length. Nonhelical peptides, having a similar primary but different secondary structure, give rise to very different redox potentials. The ramifications of these findings to biological systems are significant in that they provide further evidence that the redox properties of a metal center are influenced by factors that go beyond the primary ligand sphere and thus for the involvement of long-range interactions. The Fc group is clearly sensitive to the shape of the peptide. These effects are currently under more detailed investigation [45] in order to gain further insight into the electronic structure of these ferrocenoyl peptides. Although we are not yet in a position to distinguish between "sensing" coordination or "sensing" conformation changes, this effect is of interest because it may allow the development of peptidic sensors.
最近的研究清楚地表明，碳二亚胺方案在温和条件下将氧化还原活性的Fc部分连接到氨基酸和肽的N端侧的效用，产生稳定且通常为晶体的产物，便于通过X射线晶体学进行结构分析。对Fc肽的电化学研究表明，氧化还原电位受氨基酸序列的影响很大。Fc部分对与其相连的肽中发生的结构变化敏感。对于螺旋状的Fc-寡聚脯氨酸，随着寡聚脯氨酸链长度的增加，Fc基团的氧化还原电位使其更容易被氧化。具有相似一级结构但二级结构不同的非螺旋肽会产生非常不同的氧化还原电位。这些发现对生物系统的影响重大，因为它们进一步证明金属中心的氧化还原性质受超出一级配体球的因素影响，因此涉及远程相互作用。Fc基团显然对肽的形状敏感。目前正在对这些效应进行更详细的研究[45]，以便进一步深入了解这些二茂铁酰肽的电子结构。尽管我们尚无法区分“传感”配位或“传感”构象变化，但这种效应很有趣，因为它可能有助于开发肽类传感器。
