| Item type |
学位論文 / Thesis or Dissertation(1) |
| 公開日 |
2010-02-22 |
| タイトル |
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タイトル |
Resonance Raman Investigation of Protein Dynamics Studies on Myoglobin: Information Transmission and Energy Funneling Mechanisms |
| タイトル |
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タイトル |
Resonance Raman Investigation of Protein Dynamics Studies on Myoglobin: Information Transmission and Energy Funneling Mechanisms |
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言語 |
en |
| 言語 |
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言語 |
eng |
| 資源タイプ |
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資源タイプ識別子 |
http://purl.org/coar/resource_type/c_46ec |
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資源タイプ |
thesis |
| 著者名 |
高, 影
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| フリガナ |
ガオイン
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| 著者 |
GAO, Ying
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| 学位授与機関 |
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学位授与機関名 |
総合研究大学院大学 |
| 学位名 |
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学位名 |
博士（理学） |
| 学位記番号 |
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内容記述タイプ |
Other |
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内容記述 |
総研大甲第1013号 |
| 研究科 |
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|
値 |
先導科学研究科 |
| 専攻 |
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値 |
22 光科学専攻 |
| 学位授与年月日 |
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学位授与年月日 |
2006-09-29 |
| 学位授与年度 |
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値 |
2006 |
| 要旨 |
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内容記述タイプ |
Other |
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内容記述 |
The iron protoporphyrin IX（<i>b</i> type heme）exists as a reaction center in most of the<br />heme proteins as a prosthetic group which bound with the protein matrix. It carries out<br />various functions including the diatomic gaseous ligand storage and transport，electron<br />transfer，oxidization，peroxidization，catalysis and signaling process and so on．For <br />investigating the active center, heme-iron-ligand complex，IR and visible RR spectroscopy<br />have revealed the heme environment structure and the ligand discrimination mechanism<br />for many heme proteins．Furthermore，electron paramagnetic resonance spectroscopy<br />and quantum mechanism study have been used to revealing the reaction mechanism of<br />heme enzyme．However, in any cases the accompanying conformational changes in<br />protein moiety always occur for regulating protein function as revealed by x-ray<br />crystallography. It appears quite important to establish a correlation between the active<br />center, heme，and the protein matrix for understanding the essential mechanism for<br />heme proteins. Also，this issue has attracted a lot of concerns from many fields. The<br />nature utilizes <i>b</i> type heme as the most common structure among the four kinds of hemes<br />that contain same framework but altered substitutions. Therefore, it is easy to propose<br />that the side chain of heme could play important role in regulation of protein structure<br />and function, and this propose is consistent with the discoveries from more and more<br />experimental data that side chains are involved in many reactions related with protein<br />functions. In this study, the interactions between heme and protein matrix as well as solvent leading<br />to intramolecular transduction of structural information and intermolecular energy transfer were<br />systematically investigated by using Mb. Those interactions include the covalent bond and the<br />hydrogen bonds between heme and globin and spatial collision between heme side chains and water<br />moleculs．<br /> In order to investigate the transmission of a binding slgnal of a gaseous ligand from the<br />ligand binding site?heme，to protein moiety in gas sensory heme proteins，we applied UVRR<br />spectroscopy to myoglobin as a model. UVRR spectroscopy is known as an excellent tool for<br />monitoring protein conformational changes. First of all，we determined the changes of conformation<br />in globin that occur upon binding of CO，NO，or O<small>2</small>to heme. Specifically，NO induces spectral<br /> changes in Trp residues of A-helix that are significantly different from those induced by O<small>2</small>or CO<br />binding. On the other hand，binding of O<small>2</small> to heme produces spectral changes in the Tyr residues of<br /> H-helix that are difftrent from those induced by CO or NO binding. The UVRR results demonstrate<br />that the heme discriminates among different ligands by driving corresponding conformational changes<br /> in the globin matrix. In order to explore the signaling pathway through His93 covalent bond，and 6-or<br />7-propionate hydrogen bonding network，we extended measurements to mutant-and heme-modified<br />Mbs in a similar way to native Mb, and investigated how they are responsible for transmitting<br />structural changes from ligand binding site--heme to globin for difftrent ligands. The experimental<br />results demonstrate that the cleavage of Fe-His93 covalent bond eliminates communication to the<br />C-terminal of the H-helix and that 7-propionate hydrogen-bonding network is essential for<br />transmitting the CO or NO binding signal to the N-and C-termini. Finally，6-propionate is important<br />only for NO binding. Thus，the hydrogen-bonding network in the protein appears to be critical for<br />intramolecular slgnal transduction in gas sensory heme proteins.<br /> Furthermore, pathway of vibrational energy dissipation from the heme to<br />surrounding protein matrix and solvent following CO photolysis in the fast time<br />component (≤10 ps）was investigated by using picosecond time-resolved anti-Stokes<br />Raman spectroscopy. The modified-and mutant Mbs，in which the 6- or 7-propionate is<br />selectively replaced by a methyl group or related hydrogen bonds is eliminated by<br />mutagenesis was used as model systems. The time constants of population decay of<br />vibrationally excited states for two modified Mbs became significantly larger compared<br />with those of native Mb．However the corresponding values of mutants are not different<br />from those of the native Mb．This work indicates that the two heme-propionate side<br />chains are highly involved in the energy transfer from the heme to solvent through the<br />collision with surrounding water molecules and contribute equally. But the hydrogen<br />bonding interactions with protein matrix seem to contribute scarcely to this fast energy<br />transfer process．This is the first experimental data estimating the contribution of<br />individual heme<sup>-</sup>propionate side chains to the vibrational energy transfer from the heme<br />to the surroundings． |
| 所蔵 |
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値 |
有 |
| フォーマット |
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内容記述タイプ |
Other |
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内容記述 |
application/pdf |
要旨・審査要旨 (290.8 kB)
