頁籤選單縮合
題名 | The Hydrophobic Pocket of 24P3 Protein from Mouse Uterine Luminal Fluid: Fatty Acid and Retinol Binding Activity and Predicted Structural Similarity to Lipocalins= |
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作者 | Chu,S. T.; Chen,Y. H.; Lin,H. J.; Huang,H. L.; Chen,Y. H.; |
期刊 | 中央研究院生物化學研究所論文集 |
出版日期 | 19980000 |
卷期 | 24 1998[民87.] |
頁次 | 頁115-122 |
分類號 | 361.19 |
語文 | eng |
關鍵詞 | Circular dichroism; Fluorescence; Lipocalin; 24p3 protein; Uterine luminal fluid; |
英文摘要 | The conformation of 24p3 protein purified from mouse uterine luminal fluid was studied by circular dichroism spectroscopy in 200-300 nm. At pH 7.4, the spectrum in the UV region appears as one negative band with a minimum mean residue ellipticity of -3,600 deg.cm �插Ddmole �笐� " at 217 nm, suggesting a very low or no helical content, but a considerable amount of β -form, β -turn, and unordered form in the protein molecule. This agrees with the predicted secondary structures consisting of only one α-helical segment of residues 150-163 and nine segments of residues 28-35, 50-60. 67-72, 78-86,94-97, 106-114, 119-125, 136-140 and 166-172 in β -forms, which would construct two orthonormal β-sheets to form a less polar β-barrel. The environments around Trp-31 and Trp-81 of this protein were studied by intrinsic fluorescence and solute quenching. They give an emission peak at 332 nm, and only about 21% of them are accessible to quenching by acrylamide. This together with their low accessibility to either CsCI or Kl suggests that they are located in the less polar β -barrel. Hydrophobic compounds such as fatty acids, retinoids, and cholesteryl oleate in the protein solution diminish the protein fluorescence. Analysis of the fluorescence data suggests that the protein has a binding site for hydrophobic ligand. The association constants for the complex formation are 1.03 × 10 �� M �笐�, 1.92 × 10 �� M �笐� 2.38 × 10 �� M �笐� or 1.25 × 10 �� M �笐� " for cholesteryl oleate. oleic acid, retinol, or retinoic acid at pH 7.4. Analysis of the equilibrium binding data from binding assay using [H�孃-retinol and [H �孃-retinoic acid reveals a singular type of retinoid- binding site in the protein with the association constant of 4.92 × 10 �� M �笐� and 1.17 × 10 �� M �笐� for retinol and retinoic acid, respectively. Trp-31 or/ and Trp-81 is in or very near the binding site and the gross conformation of protein changes considerably as the formation of protein-ligand complex. |
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