Significance of the molecular shape of iron corrphycene in a protein pocket

Saburo Neya*, Kiyohiro Imai, Yoshitsugu Hiramatsu, Teizo Kitagawa, Tyuji Hoshino, Masayuki Hata, Noriaki Funasaki

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The iron complex of a new type of corrphycene bearing two ethoxycarbonyl (-CO2C2H5) groups on the bipyrrole moiety was introduced into apomyoglobin. The reconstituted ferric myoglobin has a coordinating water molecule that deprotonates to hydroxide with a pKa value of 7.3 and exhibits 3-10-fold higher affinities for anionic ligands when compared with a counterpart myoglobin with the same substituents on the dipyrroethene moiety. In the ferrous state, the oxygen affinity of the new myoglobin was decreased to 1/410 of the native protein. The anomalies in the ligand binding, notably dependent on the side-chain location, were interpreted in terms of a characteristic core shape of corrphycene that produces the longer and shorter Fe-N(pyrrole) bonds. The spin-state equilibrium analysis of the ferric azide myoglobin containing the new iron corrphycene supported the nonequivalence of the Fe-N(pyrrole) bonds. These results demonstrate that the trapezoidal molecular shape of corrphycene exerts functional significance when the iron complex is placed in a protein pocket.

Original languageEnglish
Pages (from-to)4238-4242
Number of pages5
JournalInorganic Chemistry
Issue number10
StatePublished - 15 May 2006

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