Self-Assembled Monolayer of a Pepstatin Fragment as a Sensing Element for Aspartyl Proteases
摘要:
通过将 11,11'-二硫代二癸酸(DTUA)与带有正己基端(Pepsta(h))的片段(Val-Val-Sta)偶联,制备出了一种新型二硫化物,其两端带有两个 Pepstatin 片段。获得的化合物(DTUA-Pepsta(h))在金电极和真空蒸发的金薄膜上形成了自组装单层(SAM),这分别通过循环伏安法和反射吸收红外光谱法得到了证实。当 SAM 修饰的金电极与天冬氨酰蛋白酶--胃蛋白酶溶液共孵育时,在以对苯二酚为探针的循环伏安图中观察到阳极和阴极峰电流均减小,电位差增大,而游离胃蛋白酶片段的共存则抑制了这些现象,这表明胃蛋白酶与 SAM 外部的片段有特异性结合。酶与 SAM 的结合率在很大程度上取决于 SAM 中片段分子的表面密度。此外,当将沉积在氨基修饰玻璃板上的金胶体阵列上的 DTUA-Pepsta(h)SAM 浸入胃蛋白酶溶液中时,玻璃板在 550 纳米波长处与金胶体局部表面等离子体共振相对应的吸收率突然升高并轻微红移,而进一步加入胃蛋白酶 A 会使吸收率逐渐降低。根据吸光度的递增和递减曲线,确定了胃蛋白酶与 SAM 上片段的结合常数 (Kassoc)。将片段修饰的 SAM 浸入 HIV-1 蛋白酶溶液中也观察到了类似的现象,这表明胃蛋白酶片段 SAM 可用于检测和去除生物液体中的酶。
Self-Assembled Monolayer of a Pepstatin Fragment as a Sensing Element for Aspartyl Proteases
摘要:
通过将 11,11'-二硫代二癸酸(DTUA)与带有正己基端(Pepsta(h))的片段(Val-Val-Sta)偶联,制备出了一种新型二硫化物,其两端带有两个 Pepstatin 片段。获得的化合物(DTUA-Pepsta(h))在金电极和真空蒸发的金薄膜上形成了自组装单层(SAM),这分别通过循环伏安法和反射吸收红外光谱法得到了证实。当 SAM 修饰的金电极与天冬氨酰蛋白酶--胃蛋白酶溶液共孵育时,在以对苯二酚为探针的循环伏安图中观察到阳极和阴极峰电流均减小,电位差增大,而游离胃蛋白酶片段的共存则抑制了这些现象,这表明胃蛋白酶与 SAM 外部的片段有特异性结合。酶与 SAM 的结合率在很大程度上取决于 SAM 中片段分子的表面密度。此外,当将沉积在氨基修饰玻璃板上的金胶体阵列上的 DTUA-Pepsta(h)SAM 浸入胃蛋白酶溶液中时,玻璃板在 550 纳米波长处与金胶体局部表面等离子体共振相对应的吸收率突然升高并轻微红移,而进一步加入胃蛋白酶 A 会使吸收率逐渐降低。根据吸光度的递增和递减曲线,确定了胃蛋白酶与 SAM 上片段的结合常数 (Kassoc)。将片段修饰的 SAM 浸入 HIV-1 蛋白酶溶液中也观察到了类似的现象,这表明胃蛋白酶片段 SAM 可用于检测和去除生物液体中的酶。
The peroral administration of(poly)peptide drugs requires the development of delivery systems, which provide a protective effect toward a gastrointestinal enzymatic attack. A promising strategy for such systems represents polymer-enzyme inhibitor conjugates in which the embedded therapeutic agent is protected. However, the practical use of polymer-inhibitor conjugates has so far been limited by high production costs of these auxiliary agents. To solve this problem for delivery systems shielding from pepsinic degradation, structurally simplified analogues of the pepsin inhibitor pepstatin A have been synthesized. The synthesis of tripeptide analogues, described by McConnell et al., led us to pursue further modifications varying the C-terminus. Our target to attach a spacer moisty-enabling the free access of pepsin to the inhibitor-should be combined with an attractive synthetic approach providing low production costs in large-scale preparation. Structure modifications comprised either the side chain of the third amino acid which served as starting compound designing the C-terminus (L-leucine, L-isoleucine, L-norvaline) as the length of the spacer link, simulated by a linear alkyl group (n-butyl, n-hexyl, and n-octyl). The inhibitory activities which have been evaluated by an enzyme assay were significantly dependent on the nature of the side chain, whereas the length of the spacer had no influence on the inhibitory effect. Analogues bearing the isobutyl or n-propyl moiety as side chain displayed a strong inhibitory effect which was comparable to that pepstatin A. These congeners represent promising auxiliary agents for the peroral administration of(poly)peptide drugs.