Schiller P W
Proc Natl Acad Sci U S A. 1972 Apr;69(4):975-9. doi: 10.1073/pnas.69.4.975.
The solution conformation of ACTH was studied by intramolecular resonance energy transfer and fluorescence depolarization with the synthetic, biologically active, derivative N(epsilon)-dansyllysine(21)-ACTH-(1-24)-tetrakosipeptide. The Förster parameters involved in energy transfer from the donor Trp(9) to the dansyl acceptor attached to the side chain of Lys(21) were determined from measurements with ACTH fragments containing either the donor or the acceptor alone. From determinations of the fluorescence quantum yields of the donor in the derivative and in the native ACTH-(1-24)-tetrakosipeptide, it was shown that besides energy transfer no additional quenching of the donor fluorescence is introduced by the presence of the acceptor. The short measured rotational relaxation time of the dansyl chromophore reflects the flexibility of the lysine side chain and justifies the use of an average value for the orientation factor in the distance calculations. The calculated intramolecular distance is remarkably independent of solvent, indicating a "random coil" situation with regard to residues 9-21.
采用分子内共振能量转移和荧光去极化方法，利用合成的、具有生物活性的衍生物N(ε)-丹磺酰赖氨酸(21)-促肾上腺皮质激素-(1 - 24)-二十四肽对促肾上腺皮质激素的溶液构象进行了研究。通过仅含有供体或受体的促肾上腺皮质激素片段的测量，确定了从供体色氨酸(9)到连接在赖氨酸(21)侧链上的丹磺酰受体的能量转移所涉及的福斯特参数。通过测定衍生物和天然促肾上腺皮质激素-(1 - 24)-二十四肽中供体的荧光量子产率，结果表明除能量转移外，受体的存在不会对供体荧光产生额外的猝灭。所测得的丹磺酰发色团较短的旋转弛豫时间反映了赖氨酸侧链的灵活性，证明在距离计算中使用取向因子的平均值是合理的。计算得到的分子内距离与溶剂显著无关，表明9 - 21位残基处于“无规卷曲”状态。
