Buku A, Price J A
Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York, NY 10029, USA.
Peptides. 2001 Dec;22(12):1987-91. doi: 10.1016/s0196-9781(01)00538-1.
Mast cell degranulating (MCD) peptide was modified in its two disulfide bridges and in the two arginine residues in order to measure the ability of these analogs to induce histamine release from mast cells in vitro. Analogs prepared were [Ala(3,15)]MCD, [Ala(5,19)]MCD, [Orn(16)]MCD, and [Orn(7,16)]MCD. Their histamine-releasing activity was determined spectrofluorometrically with peritoneal mast cells. The monocyclic analogs in which the cysteine residues were replaced pairwise with alanine residues showed three-to ten-fold diminished histamine-releasing activity respectively, compared with the parent MCD peptide. Substantial increases in activity were observed where arginine residues were replaced by ornithines. The ornithine-mono substituted analog showed an almost six-fold increase and the ornithine-doubly substituted analog three-fold increase in histamine-releasing activity compared with the parent MCD peptide. The structural changes associated with these activities were followed by circular dichroism (CD) spectroscopy. Changes in the shape and ellipticity of the CD spectra reflected a role for the disulfide bonds and the two arginine residues in the overall conformation and biological activity of the molecule.
为了测定这些类似物在体外诱导肥大细胞释放组胺的能力，对肥大细胞脱颗粒（MCD）肽的两个二硫键和两个精氨酸残基进行了修饰。制备的类似物有[Ala(3,15)]MCD、[Ala(5,19)]MCD、[Orn(16)]MCD和[Orn(7,16)]MCD。用腹膜肥大细胞通过荧光分光光度法测定了它们的组胺释放活性。与母体MCD肽相比，半胱氨酸残基被丙氨酸残基成对取代的单环类似物的组胺释放活性分别降低了三至十倍。当精氨酸残基被鸟氨酸取代时，观察到活性大幅增加。与母体MCD肽相比，鸟氨酸单取代类似物的组胺释放活性增加了近六倍，鸟氨酸双取代类似物增加了三倍。通过圆二色性（CD）光谱跟踪与这些活性相关的结构变化。CD光谱形状和椭圆率的变化反映了二硫键和两个精氨酸残基在分子整体构象和生物活性中的作用。
