Dodin G, Andrieux M, al Kabbani H
Institut de Topologie et de Dynamique des Systèmes de l'Université Paris, France.
Eur J Biochem. 1990 Nov 13;193(3):697-700. doi: 10.1111/j.1432-1033.1990.tb19389.x.
The unprotonated form of the anti-tumor alkaloid ellipticine binds to beta-lactoglobulins A and B from bovine milk with an affinity constant of 7 +/- 3 x 10(5) M-1. There is one binding site/dimeric protein molecule (the stable form at medium pH). The attachment site is not the beta-barrel nor the hydrophobic site identified as the retinol site in beta-lactoglobulin but a domain located at the interface of the two monomeric units where the ligand lies close to Trp61 of both polypeptide chains. The positive binding enthalpy observed in temperature-jump relaxation experiments is overcome by a strong entropy increase, tentatively thought to result from water release at the binding domain. Accordingly, desolvation is assumed to be the rate-determining step in the process of ellipticine binding.
抗肿瘤生物碱玫瑰树碱的未质子化形式与牛乳中的β-乳球蛋白A和B结合，亲和常数为7±3×10⁵ M⁻¹。每个二聚体蛋白分子（中等pH下的稳定形式）有一个结合位点。结合位点既不是β-桶结构，也不是在β-乳球蛋白中被确定为视黄醇位点的疏水位点，而是位于两个单体单元界面的一个结构域，配体在此处靠近两条多肽链的色氨酸61。在温度跳跃弛豫实验中观察到的正结合焓被强烈的熵增加所抵消，初步认为这是由于结合结构域处的水释放所致。因此，去溶剂化被认为是玫瑰树碱结合过程中的速率决定步骤。
