| Item type |
学術雑誌論文 / Journal Article(1) |
| 公開日 |
2014-01-08 |
| タイトル |
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タイトル |
Innocuous character of [ethylenebis(oxyethylenenitrilo)]tetraacetic acid and EDTA as metal-ion buffers in studying Ca2+ binding by alpha-lactalbumin |
| タイトル |
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タイトル |
Innocuous character of [ethylenebis(oxyethylenenitrilo)]tetraacetic acid and EDTA as metal-ion buffers in studying Ca2+ binding by alpha-lactalbumin |
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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_6501 |
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資源タイプ |
journal article |
| アクセス権 |
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アクセス権 |
metadata only access |
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アクセス権URI |
http://purl.org/coar/access_right/c_14cb |
| 著者 |
MITANI, Masahiro
HARUSHIMA, Yoshiaki
KUWAJIMA, Kunihiro
IKEGUCHI, Masamichi
SUGAI, Shintaro
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| 著者別名 |
桑島, 邦博
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| 抄録 |
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内容記述タイプ |
Abstract |
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内容記述 |
The binding of EGTA and EDTA to alpha-lactalbumin, first demonstrated by Kronman and Bratcher (Kronman, M. J., and Bratcher, S. C. (1983) J. Biol. Chem. 258, 5707-5709) and afterwards regarded as a significant source of error in estimating the binding constant of Ca2+ to the protein, has been investigated by comparison of the thermal unfolding curves of the protein in the absence and presence of the chelators and also by measuring the NMR spectra of the protein, the chelators, and the protein-chelator mixtures. The unfolding curve in the presence of a large excess of each chelator has been found to be identical to that in the absence of chelator, indicating that there is essentially no interaction between the chelators and alpha-lactalbumin. The NMR results have also supported this conclusion, and the innocuous character of these chelators as metal-ion buffers in studying the Ca2+-binding properties of alpha-lactalbumin is demonstrated. In order to re-examine the binding constant for Ca2+ of alpha-lactalbumin without the aid of chelating metal-ion buffers, the thermal unfolding curve of the protein in the presence of 0.1 mM excess Ca2+ but without chelators has been compared with the unfolding curve in the absence of Ca2+ at a constant concentration of Na+ (0.010 or 0.10 M) at pH 7.0. The binding constant of alpha-lactalbumin can be calculated from the increment of melting temperature caused by the presence of Ca2+ and from the enthalpy and heat capacity changes in the unfolding. Because Ca2+ binding to the unfolded protein can be neglected under the conditions employed, the binding constant evaluated corresponds to the binding constant to protein that has native structure. The constant obtained is 3-5 X 10(9) M-1 after corrections for binding of Na+ to the protein and for ionic strength, and this shows excellent agreement with the corresponding value previously estimated (2.9 +/- 1.0 X 10(9) M-1), although the latter value was obtained in the presence of EDTA. The apparent Ca2+-binding constant that has been discussed in most previous studies, without taking account of the folding-unfolding equilibrium associated with the binding process, also depends on the concentration of monovalent cations such as Na+, and the present results lead to values of 1.5 X 10(8) and 8.7 X 10(6) M-1 at 0.01 and 0.1 M Na+, respectively. |
| 書誌情報 |
Journal of Biological Chemistry
en : Journal of Biological Chemistry
巻 261,
号 19,
p. 8824-8829,
発行日 1986-07-05
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| 出版者 |
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出版者 |
American Society for Biochemistry and Molecular Biology |
| ISSN |
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収録物識別子タイプ |
ISSN |
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収録物識別子 |
0021-9258 |
| PubMed番号 |
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識別子タイプ |
PMID |
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関連識別子 |
3087980 |
| 権利 |
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権利情報 |
© 2014 by American Society for Biochemistry and Molecular Biology |
| 関連サイト |
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識別子タイプ |
URI |
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関連識別子 |
http://www.jbc.org/content/261/19/8824.short |
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関連名称 |
American Society for Biochemistry and Molecular Biology |
