IMPORTANCE OF ALIPHATIC SIDE-CHAIN STRUCTURE AT POSITION-2 AND POSITION-3 OF THE INSULIN-A CHAIN IN INSULIN-RECEPTOR INTERACTIONS
IMPORTANCE OF ALIPHATIC SIDE-CHAIN STRUCTURE AT POSITION-2 AND POSITION-3 OF THE INSULIN-A CHAIN IN INSULIN-RECEPTOR INTERACTIONS
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DOI：
10.1021/bi00127a023
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发表时间：
1992-03-31
期刊：
影响因子：
2.9
通讯作者：
TAGER, HS
中科院分区：
文献类型：
--
作者：
NAKAGAWA, SH;TAGER, HS
为了评估天然存在的突变型人胰岛素和歌山胰岛素（[Leu(A3)]胰岛素，0.2%相对效力）受体结合效力大大降低的原因，我们检查了（通过基于N（α）-Phe（B1），N（ε）-Lys（B29）-双乙酰胰岛素的胰岛素类似物的半合成）A2位和A3（分别为 Ile 和 Val）指导胰岛素与其受体的相互作用。分析了在 A2 或 A3 位点带有甘氨酸、丙氨酸、α-氨基正丁酸、正缬氨酸、正亮氨酸、缬氨酸、异亮氨酸、别异异亮氨酸、苏氨酸、叔亮氨酸或亮氨酸的类似物在竞争 I-125 标记的胰岛素与分离的犬肝细胞的结合方面的效力，以及带有 A 链氨基缺失的类似物末端或B链羧基末端。还通过远紫外 CD 和 Co2+ 配合物的吸收光谱分析了选定的类似物。我们的结果表明 (a) Ile 和 Val 在位置 A2 上表现良好，而具有其他侧链的残基（包括具有直链、选择性配置的 β 分支或 γ 分支）的残基表现出 1-5% 范围内的相对受体结合效力； (b) A3位侧链结构具有更大的灵活性，异亮氨酸、异位异亮氨酸、α-氨基正丁酸和叔亮氨酸表现出11-36%范围内的相对受体结合效力； (c) A2 和 A3 位点的同时替换以及相关类似物中胰岛素 B 链 COOH 末端结构域的缺失，产生累积效应。这些发现是针对胰岛素受体相互作用模型进行讨论的，该模型涉及残基 A2 的结构导向作用、残基 A3 与受体的直接相互作用以及多个单独定义的结构和构象调整元件。
In order to evaluate the cause of the greatly decreased receptor-binding potency of the naturally occurring mutant human insulin Insulin Wakayama ([Leu(A3)]insulin, 0.2% relative potency), we examined (by the semisynthesis of insulin analogues based on N(alpha)-Phe(B1),N(epsilon)-Lys(B29)-bisacetyl-insulin) the importance of aliphatic side chain structure at positions A2 and A3 (Ile and Val, respectively) in directing the interaction of insulin with its receptor. Analogues bearing glycine, alanine, alpha-amino-n-butyric acid, norvaline, norleucine, valine, isoleucine, allo-isoleucine, threonine, tert-leucine, or leucine at positions A2 or A3 were assayed for their potencies in competing for the binding of I-125-labeled insulin to isolated canine hepatocytes, as were analogues bearing deletions from the A-chain amino terminus or the B-chain carboxyl terminus. Selected analogues were also analyzed by far-UV CD and absorption spectroscopy of Co2+ complexes. Our results identify that (a) Ile and Val serve well at position A2, whereas residues with other side chains (including those with straight chains, alternatively configured beta-branches, or a gamma-branch) exhibit relative receptor-binding potencies in the range 1-5%; (b) greater flexibility is allowed side-chain structure at position A3, with Ile, allo-Ile, alpha-amino-n-butyric acid, and tert-Leu exhibiting relative receptor-binding potencies in the range 11-36%; and (c) simultaneous replacements at positions A2 and A3, and deletions of the COOH-terminal domain of the insulin B chain in related analogues, yield cumulative effects. These findings are discussed with respect to a model for insulin-receptor interactions that involves a structure-orienting role for residue A2, the direct interaction of residue A3 with receptor, and multiple separately defined elements of structure and of conformational adjustment.