CONFORMATIONAL STUDIES OF GROWTH FACTORS AND TRANSFORMING RELATED PEPTIDES

本课题的研究目标是：(1)研究黄曲霉毒素的作用机制。 基于生长因子分子的促有丝分裂活性 构思和(2)开发和设计具体的和 细胞黏附和迁移的竞争性多肽抑制物 在入侵期间。到目前为止所获得的结果包括：(1)四个循环 人表皮生长因子(EGb)的多肽及其类似物 已经合成了转化生长因子-α。 采用高稀释法和高效液体提纯 高效液相色谱(HPLC)。(2)使用放射受体分析，所有 四个人工合成的环肽竞争结合~(125)I- EGF在100微米的浓度下与EGF受体结合。循环 (ALA(20))EGF(14-31)和周期EGF(20-31)能够阻断 30%和20%的(125)I-EGF与受体的结合， 分别进行了分析。在转化生长因子-α的情况下，clycic(Ala(21))转化生长因子(16- 32)和循环转化生长因子(21-32)将分别取代20%和11%的 (125)I-EGF分别与受体结合。(3)使用各种两个- 三维核磁共振技术， 两种转化生长因子-β-氨基酸的质子共振谱 分配了17聚体和转化生长因子-12聚体，核间 得到了质子-质子在空间中的距离。后者 信息被用来产生能量最小化的肽 使用计算机程序的结构。(4)四细胞识别 多肽类似物已被合成和提纯。(5) GRGDS和GRGES的圆二色谱(CD)研究 甲醇揭示GRGDS具有更高的有序性 二级结构。(6)天冬氨酸和谷氨酸的pK(A)值 Cd pH滴定测定GRGXS系列 光谱，分别为2.50和3.10，均为 低于单个氨基酸(天冬氨酸3.86，4.01 对于Glu)。

The objectives of this project are (1) to study the mechanism of mitogenic activities of growth factors based on their molecular conformation and (2) to develop and design specific and competitive peptide inhibitor of cell adhesion and migration during invasion. Results obtained so far include: (1) Four cyclic peptides, analogues of human epidermal growth factor (EGB) and transforming growth factor (TGF)-alpha, have been synthesized by high dilution method and purified by high performance liquid chromatography (HPLC). (2) Using a radioreceptor assay, all four of synthetic cyclic peptides competed binding of (125) I- EGF to the EGF receptor at a concentration of 100 uM. Cyclic (Ala(20)) EGF (14-31) and cyclic EGF (20-31) were able to block 30% and 20% of the binding of (125) I-EGF to the receptor, respectively. In the case of TGF-alpha, clycic (Ala(21)) TGF (16- 32) and cyclic TGF (21-32) would displace 20% and 11% of the (125) I-EGF to the receptor, respectively. (3) Using various two- dimensional nuclear magnetic resonance (NMR) techniques, the proton resonances of the individual amino acids for both TGF- 17mer and TGF-12mer were assigned, and the internuclear proton-proton distances through space were obtained. The latter information was used to generate energy-minimized peptide structures using the computer program. (4) Four cell recognition peptide analogues have been synthesized and purified. (5) Circular dichroism (CD) studies of GRGDS and GRGES in methanol reveal that GRGDS has a more highly ordered secondary structure. (6) The pK(a) value of Asp and Glu in the GRGXS series, determined by pH titration using CD spectroscopy, were 2.50 and 3.10, respectively, which were both lower than that of the individual amino acids (3.86 for Asp, 4.01 for Glu).