Silkworm diapause hormone, structure-activity relationships indispensable role of C-terminal amide.
Silkworm diapause hormone, structure-activity relationships indispensable role of C-terminal amide.
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DOI：
10.1016/0965-1748(94)90137-6
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发表时间：
1994-12
影响因子：
3.8
通讯作者：
S. Suwan;M. Isobe;O. Yamashita;H. Minakata;K. Imai
中科院分区：
文献类型：
--
作者：
S. Suwan;M. Isobe;O. Yamashita;H. Minakata;K. Imai
为了确定家蚕滞育激素的构效关系，用固相Fmoc方法合成了一系列从母体C末端开始具有不同链长的多肽类似物，以及具有相同序列的与游离酸C末端相同的类似物，并用高效液相色谱进行了进一步的纯化。生物活性测定表明，含有游离酸C末端的类似物无活性。只有酰胺化的C-末端类似物才能显示这些较短的链的保留活性，其中活性依赖于链的长度。活性多肽需要两个最小的元件，即C-末端的序列和酰胺化。对蚕蛹血淋巴中C-末端酰胺化或游离酸类似物的酶消化没有差异。因此，游离酸类似物没有水解酶活性并不是因为选择性地比C-端酰胺化多肽的水解速度快。这表明，某些高阶结构的存在可能参与了激素活性的表达，或者游离酸末端的负电荷可能有害于适当的配体受体相互作用。由于大多数疏水氨基酸位于C-末端附近，C-末端的疏水性和酰胺化都是滞育激素活性所必需的结构。
To determine the structure—activity relationships of the silkworm diapause hormone, a series of peptide analogs having different chain lengths starting from the parent C-terminus and analogs having identical sequences with free acid C-termini were chemically synthesized by solid-phase Fmoc methodology and were further purified by HPLC. Bioassay showed that the analogs with free acid C-termini were non active. The retained activities of those shorter chains were shown only with amidated C-terminal analogs among which the potency depended on the length of the chain. The active peptides required two minimal elements; namely the sequence near and the amidation of the C-terminus. There was no difference in enzymatic digestion of the C-terminally amidated or free acid analogs in pupal haemolymph. Hence the absence of DH activity of the free acid analogs was not because of being selectively hydrolyzed faster than the C-terminally amidated peptides. This suggested that existence of a certain higher order structure could be involved in expressing hormonal activity, or that the negative charge of the free acid terminus may be deleterious to a proper ligand receptor interaction. Since most of the hydrophobic amino acids were located near the C-terminal portion, both the hydrophobicity of the portion near and the amidation of the C-terminus were indispensable structures for diapause hormone activity.