Ma J N, Zhu B L, Chi C W
Shanghai Institute of Biochemistry, Academia Sinica, Shanghai, China.
Diabetes. 1991 Sep;40(9):1218-22. doi: 10.2337/diab.40.9.1218.
A new active peptide was purified from the acid-alcohol extract of pork pancreas. It markedly suppressed the insulin activity detected by either in vivo mouse convulsion assay or in vitro free-fat cell assay. When the extract was subjected to chromatography on a carboxymethylcellulose column, the insulin fraction completely passed through the column, whereas the glucagon fraction was absorbed. The fact that the total apparent biological activity of insulin in the exclusive eluate was higher than in the original extract and the insulin radioimmunoactivity remained unchanged led to the discovery of a potent insulin inhibitor in the extract. The inhibitor was separated from glucagon and insulin in the extract by ion-exchange chromatography on a carboxymethylcellulose column followed by gel filtration on a Bio-Gel P-6 column and finally purified by reverse-phase high-performance liquid chromatography (HPLC) on a C-18 column. The antagonistic effect of this inhibitor on insulin was dose dependent with an ED50 of 2 x 10(-10) M, which was the same level used for insulin in vitro assay (1.7 x 10(-10) M). Amino acid analysis of the inhibitor showed that it was rich in arginine and glycine. It was estimated to be approximately 3000 Mr. The NH2-terminal of the peptide was proved to be blocked because it could not be degraded by Edman degradation. Based on the physicochemical and biochemical characteristics of the inhibitor and compared with other active peptides known to be in the pancreas, the inhibitor is probably a new active peptide that might play an important role in homeostasis of carbohydrate metabolism.
从猪胰腺的酸醇提取物中纯化出一种新的活性肽。它能显著抑制通过体内小鼠惊厥试验或体外游离脂肪细胞试验检测到的胰岛素活性。当提取物在羧甲基纤维素柱上进行层析时，胰岛素部分完全通过该柱，而胰高血糖素部分被吸附。仅洗脱液中胰岛素的总表观生物活性高于原始提取物，且胰岛素放射免疫活性保持不变，这一事实导致在提取物中发现了一种强效的胰岛素抑制剂。通过在羧甲基纤维素柱上进行离子交换层析，随后在Bio-Gel P-6柱上进行凝胶过滤，最后在C-18柱上进行反相高效液相色谱（HPLC），将抑制剂从提取物中的胰高血糖素和胰岛素中分离出来。该抑制剂对胰岛素的拮抗作用呈剂量依赖性，ED50为2×10⁻¹⁰ M，这与胰岛素体外测定所用水平（1.7×10⁻¹⁰ M）相同。对该抑制剂的氨基酸分析表明，它富含精氨酸和甘氨酸。估计其分子量约为3000。该肽的氨基末端被证明是封闭的，因为它不能被埃德曼降解法降解。根据该抑制剂的物理化学和生化特性，并与已知存在于胰腺中的其他活性肽进行比较，该抑制剂可能是一种新的活性肽，可能在碳水化合物代谢的体内平衡中发挥重要作用。
