| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1991: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1990: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1989: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
The resonance Raman spectra of metalloporphyrins such as tetrakis(sulfophenyl)porphine(Me-TPPS)and tetrakis(1-methylpyridinium-4-yl)porphine(Me-TMPyP)by the use of the stable isotopes in solutions and on the modified ion-exchange resins(Me-P_r)have been investigated in order to study the reaction mechanisms of enzyme-like functions of metalloporphyrins.
1. The frequencies of metal-ligand stretching vibrations of Me-TMPyP assigned based on the metal-isotope effects in solid and solutions were almost same as that of Me-TMPyP on the modified resins, indicating the metal-ligand bonds of Me-TMPyP were not so different among in solid, solutions and on the modified resins. The pH of solutions affected the number of porphyrin-core protons and the axial-ligand to metal ion of porphyrin ring, and the foreign substances affected not only the coordination number and spin states of central metal ion but also core-size of porphyrin ring. Moreover, metalloporphyrins on the modified resins showed some photoreactions such as photoreduction, photodemetallation and photodeligation by laser-irradiation.
2. An oxidation state of central metal ion of porphyrin ring varied in the course of the enzyme-like catalytic reaction of metalloporphyrins on the modified resins. For example, in case of an uricase-like activity, Me^<3+>-P_r was reduced to Me^<2+>-P_r with oxidizing uric acid to allantoin, and Me^<2+>-P_r was oxidized to Me^<3+>-P_rby oxygen in the system. Me-P_r exhibited its catalytic function for uric acid by repeating this redox cycle of Me-P_r. In the continuously catalytic function of uricase- and catalase-like reactions, H_2O_2 was produced with oxidation of uric acid by an uricase-like function of M-P_r, and continuously a part of H_2O_2 reacted with methanol to produce formaldehyde by a catalase-like function of M-P_r.
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