2004 Fiscal Year Final Research Report Summary
Evaluation and Modification of Chemical Functions of Dicopper Proteins
| Project/Area Number |
15350105
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Chemistry related to living body
|
|---|
| Research Institution | Osaka City University |
|---|
Principal Investigator |
ITOH Shinobu Osaka City University, Graduate School of Science, Department of Chemistry, Professor, 大学院・理学研究科, 教授 (30184659)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TACHI Yoshimitsu Osaka City University, Graduate School of Science, Department of Chemistry, Research Assistant, 大学院・理学研究科, 助手 (50336757)
|
|---|
| Project Period (FY) |
2003 – 2004
|
| Keywords | Tyrosinase / Dioxygen Activation / Dicopper-Dioxygen Complex / Phenol Oxidation / Reaction Mechanism / Copper Protein / Peroxo Complex / Oxo Complex |
|---|
| Research Abstract |
[1] Evaluation of Enzymatic Activities of Mushroom Tyrosinase:
Catalase and peroxygenase activity of mushroom tyrosinase have been investigated kinetically by using amperometric methods. Quantitative analysis on the substituent effects of a series of p-substituted phenols in the peroxygenase activity has demonstrated that the reaction mechanism is the same to that of the phenolase reaction, that is the electrophilic aromatic substitution mechanism by a side-on peroxo dicopper(II) intermediate. The same peroxo intermediate has been imprecated to be involved as an intermediate of catalase activity. Furthermore, catecholase activity has investigated in the same manner to demonstrate that the oxidation of phenols by the side-on peroxo dicopper(II) intermediate involves a similar electrophilic tonic mechanism.
[2] Purification of Neurospora crassa Tyrosinase :
Neurospora crassa tyrosinase has been isolated and purified in order to examine the catalytic functions and mechanisms of tyrosinase fr
… More
om different origins.
[3] Oxidation Mechanism of Phenols by Dicopper-Dioxygen Complexes :
The first systematic study on the oxidation of neutral phenols by the (μ-η^2:η^2-peroxo) dicopper (II) complex and the bis (μ-oxo) dicopper (III) complex. Comparison of the rate-dependences in the oxidation of phenols by the Cu_2/O_2 complexes on the one-electron oxidation potentials of the phenol substrates provides profound insights into the mechanistic basis of the phenol-oxidation as well as the electron-transfer oxidation ability of the Cu_2/O_2 complexes.
[4] Ligand Effects on the Copper(I)-Dioxygen Reactivity :
Structure, physicochemical properties, and dioxygen-reactivity of copper (I) complexes supported by N, N-bis(6-methyl-2-pyridylmethyl)-2-phenylethylamine tridentate ligands have been compared to those of copper (I) complex 1 of N, N-bis[2-(2-pyridyl)ethyl]-2-phenylethylamine tridentate ligand and copper (I) complex 3 of N, N-bis(2-pyridylmethyl)-2-phenylethylamine tridentate ligand. Oxygenation of 2 at a low temperature gave a side-on peroxo dicopper (II) complex as in the case of 1, but its O-O bond was relatively weakened as compared to that of the peroxo complex derived from 1. On the other hand, 3 reacted with dioxygen very rapidly to give a bis (μ-oxo) dicopper (III) complex. These results can be interpreted by taking account of the difference in electron donor ability of the ligands. Less
|
