Peavy D E, Brunner M R, Duckworth W C, Hooker C S, Frank B H
J Biol Chem. 1985 Nov 15;260(26):13989-94.
The biological activities of several derivatives of human proinsulin (HPI) containing peptide bond cleavages or peptide deletions in the connecting peptide region were examined in vivo in rats and in several in vitro systems. The two derivatives which were tested in vivo, split (32-33)HPI and des-(64,65)HPI, both demonstrated greater potency in lowering blood glucose than did intact HPI. The receptor binding affinities of split (65-66)HPI, des-(57-65)HPI, des-(64,65)HPI, des-(33-56)HPI, des-(31,32)HPI, split (32-33)HPI, and split (56-57)HPI were examined in cultured IM-9 lymphocytes, freshly isolated rat adipocytes, and purified rat liver membranes and were compared to the binding of intact HPI and insulin. In these systems, HPI averaged approximately 1% of the activity of insulin. Modification of proinsulin in the connecting peptide region near the A-chain of insulin to form split (65-66)HPI, des-(57-65)HPI, des-(64,65)HPI, or des-(33-56)HPI resulted in an increase in affinity for receptor binding ranging from 11 to 27-fold over that of intact HPI. In contrast, modifications near the B-chain of insulin to form either des-(31,32)HPI or split (32-33)HPI resulted in roughly a 5-fold increase in affinity, whereas a cleavage within the connecting peptide to form split (56-57)HPI showed only a 2-fold increase in affinity as compared to intact HPI. The biological potencies of these materials were examined in isolated rat adipocytes. At high concentrations (10(-7) M), each derivative produced the same maximal response. At lower concentrations, differences in the relative potencies paralleled the differences in receptor binding affinity previously noted.
在大鼠体内以及多个体外系统中，对人胰岛素原（HPI）在连接肽区域含有肽键裂解或肽缺失的几种衍生物的生物活性进行了检测。在体内进行测试的两种衍生物，裂解（32 - 33）HPI和去（64,65）HPI，在降低血糖方面均显示出比完整HPI更强的效力。在培养的IM - 9淋巴细胞、新鲜分离的大鼠脂肪细胞和纯化的大鼠肝膜中检测了裂解（65 - 66）HPI、去（57 - 65）HPI、去（64,65）HPI、去（33 - 56）HPI、去（31,32）HPI、裂解（32 - 33）HPI和裂解（56 - 57）HPI的受体结合亲和力，并与完整HPI和胰岛素的结合情况进行了比较。在这些系统中，HPI的活性平均约为胰岛素的1%。胰岛素原在靠近胰岛素A链的连接肽区域进行修饰形成裂解（65 - 66）HPI、去（57 - 65）HPI、去（64,65）HPI或去（33 - 56）HPI后，与完整HPI相比，受体结合亲和力增加了11至27倍。相比之下，在胰岛素B链附近进行修饰形成去（31,32）HPI或裂解（32 - 33）HPI，亲和力增加了约5倍，而连接肽内的裂解形成裂解（56 - 57）HPI，与完整HPI相比，亲和力仅增加了2倍。在分离的大鼠脂肪细胞中检测了这些物质的生物效力。在高浓度（10⁻⁷ M）下，每种衍生物产生相同的最大反应。在较低浓度下，相对效力的差异与先前观察到的受体结合亲和力差异平行。
