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Exchange behavior of the H-bonded amide protons in the 3 to 13 helix of ribonuclease S
https://ir.soken.ac.jp/records/4126
https://ir.soken.ac.jp/records/4126e2482cc2-30df-4463-b3a1-e43ec99680a2
| Item type | 学術雑誌論文 / Journal Article(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2013-12-25 | |||||
| タイトル | ||||||
| タイトル | Exchange behavior of the H-bonded amide protons in the 3 to 13 helix of ribonuclease S | |||||
| タイトル | ||||||
| タイトル | Exchange behavior of the H-bonded amide protons in the 3 to 13 helix of ribonuclease S | |||||
| 言語 | en | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_6501 | |||||
| 資源タイプ | journal article | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
KUWAJIMA, Kunihiro
× KUWAJIMA, Kunihiro× BALDWIN, Robert L |
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| 著者別名 |
桑島, 邦博
× 桑島, 邦博 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | The preceding article shows that there are eight highly protected amide protons in the S-peptide moiety of RNAase S at pH 5, 0°C. The residues with protected NH protons are 7 to 13, whose amide protons are H-bonded in the 3 to 13 α-helix, and Asp14, whose NH proton is H-bonded to the CO group of Val47. We describe here the exchange behavior of these eight protected protons as a function of pH. Exchange rates of the individual NH protons are measured by 1H nuclear magnetic resonance in D2O. A procedure is used for specifically labeling with 1H only these eight NH protons. The resonance assignments of the eight protons are made chiefly by partial exchange, through correlating the resonance intensities in spectra taken when the peptide is bound and when it is dissociated from S-protein in 3·5 m-urea-d4, in D2O, pH 2·3, −4°C. The two remaining assignments are made and some other assignments are checked by measurements of the nuclear Overhauser effect between adjacent NH protons of the α-helix. There is a transition in exchange behavior between pH 3, where the helix is weakly protected against exchange, and pH 5 where the helix is much more stable. At pH 3·1, 20°C, exchange rates are uniform within the helix within a factor of two, after correction for different intrinsic exchange rates. The degree of protection within the helix is only 10 to 20-fold at this pH. At pH 5·1, 20°C, the helix is more stable by two orders of magnitude and exchange occurs preferentially from the N-terminal end. At both pH values the NH proton of Asp14, which is just outside the helix, is less protected by an order of magnitude than the adjacent NH protons inside the helix. Opening of the helix can be observed below pH 3·7 by changes in chemical shifts of the NH protons in the helix. At pH 2·4 the changes are 25% of those expected for complete opening. Helix opening is a fast reaction on the n.m.r. time scale (τ ≪ 1 ms) unlike the generalized unfolding of RNAase S which is a slow reaction. Dissociation of S-peptide from S-protein in native RNAase S at pH 3·0 also is a slow reaction. Opening of the helix below pH 3·7 is a two-state reaction, as judged by comparing chemical shifts with exchange rates. The exchange rates at pH 3·1 are predicted correctly from the changes in chemical shift by assuming that helix opening is a two-state reaction. At pH values above 3·7, the nature of the helix opening reaction changes, These results indicate that at least one partially unfolded state of RNAase S is populated in the low pH unfolding transition. |
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| 書誌情報 |
Journal of Molecular Biology en : Journal of Molecular Biology 巻 169, 号 1, p. 299-323, 発行日 1983-09-05 |
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| 出版者 | ||||||
| 出版者 | Elsevier | |||||
| ISSN | ||||||
| 収録物識別子タイプ | ISSN | |||||
| 収録物識別子 | 0022-2836 | |||||
| DOI | ||||||
| 識別子タイプ | DOI | |||||
| 関連識別子 | https://doi.org/10.1016/S0022-2836(83)80185-5 | |||||
| 関連名称 | 10.1016/S0022-2836(83)80185-5 | |||||
| 権利 | ||||||
| 権利情報 | © 1983 Published by Elsevier Ltd. | |||||
