STERIC REQUIREMENTS AT POSITION-B12 FOR HIGH BIOLOGICAL-ACTIVITY IN INSULIN
STERIC REQUIREMENTS AT POSITION-B12 FOR HIGH BIOLOGICAL-ACTIVITY IN INSULIN
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DOI：
10.1021/bi00061a022
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发表时间：
1993-03-16
期刊：
影响因子：
2.9
通讯作者：
KATSOYANNIS, PG
中科院分区：
文献类型：
--
作者：
HU, SQ;BURKE, GT;KATSOYANNIS, PG
胰岛素B链9-19位氨基酸残基形成的α螺旋参与其三维结构的稳定。我们已经证明，B9、B10、B12 和 B16 位点的修饰会导致类似物具有约 100% 的生物活性。 0.2% 至约相对于天然胰岛素高500%。 [B12 Asn]胰岛素显示出最低效力，其中疏水性 B12 Val 残基被亲水性 Asn 残基取代。我们现在报道了四种胰岛素类似物的合成，其中保留了疏水性，并且仅改变了 B12 区域中原子的空间排列。用 α-氨基异丁酸 (Aib)、D-Ala 和 Phe 替代 B12 Val 导致类似物在脂肪生成测定中相对于天然胰岛素的生物活性分别为 8.5%、2% 和 0.2%。 B11-B12 序列 -Leu-Val- 的倒置导致类似物显示出 3.3% 的活性。其中 B11 Leu-B12 Val 序列被 B11 Ala-B12 Ile 取代的合成 B 链无法与天然 A 链结合。我们得出结论，胰岛素中 B12 位置的 Val 残基满足涉及胰岛素结构稳定性的特殊侧链包装要求。即使 B12 位发生轻微的空间变化也会导致 B 链整体构象的扭曲，从而影响其与天然 A 链结合的能力。这种扭曲保留在相应的类似物中，这反映在生物效力的减弱上。
The alpha-helix formed by the amino acid residues 9-19 of the B-chain of insulin is involved in the stabilization of its three-dimensional structure. We have shown that modification at positions B9, B10, B12, and B16 results in analogues possessing biological activities ranging from ca. 0.2% to ca. 500% relative to that of natural insulin. The lowest potency was displayed by [B12 Asn]insulin, in which the hydrophobic B12 Val residue was replaced by the hydrophilic Asn residue. We now report the synthesis of four insulin analogues in which hydrophobicity is retained, and only the spatial arrangement of atoms in the B12 region is altered. Substitution of B12 Val with alpha-aminoisobutyric acid (Aib), D-Ala, and Phe led to analogues possessing biological activities, in lipogenesis assays, of 8.5%, 2%, and 0.2%, respectively, relative to that of natural insulin. Inversion of the B11-B12 sequence, -Leu-Val-, led to an analogue displaying 3.3% activity. A synthetic B-chain in which the B11 Leu-B12 Val sequence was replaced by B11 Ala-B12 Ile was incapable of combining with the natural A-chain. We conclude that the Val residue in the B12 position in insulin fulfills special side-chain packing requirements involved in the stability of the structure of insulin. Even slight steric alteration at position B12 results in a distortion of the overall conformation of the B-chain which affects its ability to combine with the natural A-chain. This distortion is retained in the corresponding analogue, which is reflected in diminished biological potency.