Laboratory for Condensed Matter Theory: MolecularSpectroscopy : Resonance Raman Scattering of Metal
Complexes and Heme Proteins / Vibrational OpticalActivity of Metal Porphyrins and Proteins
http://www.sci.osaka-cu.ac.jp/chem/RKINOU/index.html
Current Research and Principal Research Interests
Selected Publications
1. Current Research and Principal Research Interests
I have investigated biophysical properties of heme proteins in terms of vibrational spectroscopy
in order to elucidate the physiological functions by which the mutual interactions between
protein, heme iron and porphyrin work cooperatively. Recently, I have been focusing on twotopics, one is the electronic properties of metal porphyrins themselves, the other is theinteractions between ligands and the porphyrin ring through the heme iron. I also try to apply thespectroscopy not only to bio-related chemistry but a wide range of inorganic chemistry andmaterial science.
1)Electronic States of Porphyrins and Porphycenes: Porphycene, a tetrapyrrolic structural
isomer of porphyrin, is a new type of porphyrinoid chromophore. Resonance Raman spectra ofreduced porphycenes were measured in an effort to characterize structural changes concomitantwith chemical reduction. Frequency shifts were observed for reduced porphycenes in certain
skeletal modes. The observed RR behavior was generally consistent with the results ofvibrational analysis by quantum chemical calculations based on density functional methods. In
the course of porphycene studies, I found it worthwhile studying thoroughly resonance Raman
spectra for metal-free compounds such as N-deprotonated- and N-protonated porphyrinoid
chromophores: Some marker Raman bands shift systematically upon deprotonations, suggestingthat a coulomb interaction should be predominant for the Raman frequencies rather than MO
type interactions - electron delocalization, between a central metal ions and porphyrin ligands.
The results provided a sort of theoretical background to the empirical rules so far believed
undoubtedly.
2-1)Photodissociation and Photoreduction: Photodissociation has been utilized to investigate
the association and dissociation rate constants for ligand binding to hemoproteins to provide
insight into the relationship between structure and dynamics. I reported the first example ofphotodissociation in a ferric low-spin porphyrin complex. The fact that photolysis of 1-MeIm isinitiated by ?*-? excitation of the porphyrin suggests that there is at least one delocalized
molecular orbital in the metal complex which is responsible for the photodissociation. I would
like to elucidate the phenomenon such as photoreduction in terms of the same discussion applied
to photodissociation.
2-2)Vibrational Optical Activity: Vibrational circular dichroism studies of ligands bound tohemoproteins have been reported, the results of which give valuable new insights into theelectronic states as well as the coordination geometry of hemoproteins. The results indicate thatthe chiral environment produced by the peripheral substituents on the porphyrin ring, which giverise to a diastereotopic plane, is responsible for the generation of strong VCD of the ligands inhemeproteins, whereas specific interactions of distal residues with the porphyrin ring and theligands in halo-proteins are not always necessary. However, there still remain a couple ofproblems to be solved, different VCD signs for some ligands and the origin of the magnetictransition dipole moments.

2. Selected Publications
Related to research interest 1:
1. "Electronic and Vibrational Properties of Porphycene Anions", R. M. Gulam, T. Matsushita,and J. Teraoka, J. Phys. Chem. A, 107, 2172-2178 (2003).
2. "Resonance Raman Characterization of Porphycene Anions", R. M. Gulam, T. Matsushita, S.
Neya, N. Funasaki, and J. Teraoka, Chem. Phys. Lett., 357, 126-130 (2002).
Related to research interest 2:
3. "Photodissociation of 1-Methylimidazole Ligand in Ferric Low-Spin Iron Porphyrin", J.
Teraoka and K. Nakamoto, J. Am. Chem Soc., 122, 6301-6302 (2000).
4. "Loop Structure in Human Serum Albumin from Raman Optical Activity", J. Teraoka, A. F.
Bell, H. Lutz, and L. D. Barron, J. Raman Spectrosc., 29, 67-71, (1998).
5. "What is the Crucial Factor for Vibrational Circular Dichroism in Hemo-protein Ligands?", J.
Teraoka, N. Yamamoto, Y. Matsumoto, Y. Kyogoku, and H. Sugeta, J. Am. Chem. Soc., 118,8875-8878 (1996).
6. "UV Resonance Raman Saturation Spectroscopy of Tryptophan derivatives; PhotophysicalRelaxation Measurements with Vibrational Band Resolution", J. Teraoka, P. A. Harmon, and S.
A. Asher, J. Am. Chem. Soc., 112, 2892-2900 (1990).
7. "Structural Implication of the Heme Linked Ionization of Horseradish Peroxidase Probed bythe Fe-Histidine Stretching Raman Line", J. Teraoka and T. Kitagawa, J. Biol. Chem., 256,3969-3977 (1981).
The others:
8. "Cytochrome c-Crown Ether Complexes as Supramolecular Catalysts: Cold Active Synzymes
for Asymmetric Sulfoxide Oxidation in Methanol", A. Suzumura, D. Paul, H. Sugimoto, S.
Shinada, R. R. Julian, J. L. Beauchamp, J. Teraoka, and H. Tsukube, Inorg. Chem., 44, 904-910(2005).
9. "Mechanism of Superconductivity in the Polyhedral-network semiconductor Ba8Si46", J.
Teraoka, Y. Morimoto and S. Yamanaka, Nature Mater., 2, 653-655 (2003).
10. "Chemical Activation of Cytochrome c Proteins via Crown Ether Complexation:
Cold-Active Synzymes for Enantiomer-Selective Sulfoxide Oxidation in Methanol", D. Paul, A.
Suzumura, H. Sugimoto, J. Teraoka, S. Shinoda and H. Tsukube, J. Am. Chem. Soc., 125,11478-11479 (2003).