ISOLATION AND SEQUENCE-ANALYSIS OF A SOMATOSTATIN-LIKE POLYPEPTIDE FROM OVINE HYPOTHALAMUS
ISOLATION AND SEQUENCE-ANALYSIS OF A SOMATOSTATIN-LIKE POLYPEPTIDE FROM OVINE HYPOTHALAMUS
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DOI：
10.1021/bi00510a038
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发表时间：
1981-01-01
期刊：
影响因子：
2.9
通讯作者：
VALE, W
中科院分区：
文献类型：
--
作者：
SPIESS, J;VILLARREAL, J;VALE, W
从绵羊下丘脑中分离出表观分子量为 3000-4500 的大生长抑素样多肽 [4K（千道尔顿）生长抑素 (SS)]。获得甲硫氨酸亚砜形式的多肽。使用改进的 890 C 旋转杯测序仪对 0.6 和 1.8 nmol 4K SS 进行两次微测序分析。测序数据、氨基酸分析和C末端基团测定结果表明4K SS与猪上小肠分离的生长抑素28（SS-28）相同。没有检测到游离的半胱氨酸巯基，表明绵羊SS-28的2个半胱氨酸残基形成了分子内二硫键。除了 SS-28 的结构外，来自绵羊下丘脑的未知多肽的 N 端前 30 个残基的测序如下： H-Ile-Pro-Ile-Tyr-Glu-Lys-Lys-Tyr-Gly-Gln-Val-Pro-Met-Cys-Asp-Ala-Gly-Glu-Gln-Cys-Ala-Val-Arg-Lys-Gly-Ala-Arg-Ile-Gly-Lys-。胰蛋白酶从绵羊下丘脑 SS-28 中裂解生长抑素 (SS) 实体的选择性低于从大鼠下丘脑 12,000 道尔顿 SS 样多肽 (12K SS) 中裂解生长抑素 (SS) 实体的选择性。天然绵羊下丘脑 SS-28 能够高效抑制培养的大鼠垂体前叶细胞的生长激素释放。结果令人怀疑绵羊SS-28是否是SS前体，并表明SS-28本身可能具有调节功能。
A large somatostatin-like polypeptide of apparent MW 3000-4500 [4K (kilodalton) somatostatin (SS)] was isolated from ovine hypothalamus. The polypeptide was obtained in the methionine sulfoxide form. Two microsequence analyses of 0.6 and 1.8 nmol of 4K SS were performed with a modified 890 C spinning cup sequencer. The sequencing data together with results of amino acid analysis and C-terminal end-group determination indicated that 4K SS was identical with somatostatin-28 (SS-28) isolated from porcine upper small intestine. No free cysteine sulfhydryl group could be detected, suggesting that the 2 cysteine residues of ovine SS-28 formed an intramolecular disulfide bond. Besides the structure of SS-28, the N-terminal first 30 residues of an unknown polypeptide from ovine hypothalamus was sequenced as follows: H-Ile-Pro-Ile-Tyr-Glu-Lys-Lys-Tyr-Gly-Gln-Val-Pro-Met-Cys-Asp-Ala-Gly-Glu-Gln-Cys-Ala-Val-Arg-Lys-Gly-Ala-Arg-Ile-Gly-Lys-. Trypsin cleaved the somatostatin (SS) entity less selectively from ovine hypothalamic SS-28 than from rat hypothalamic 12,000 dalton SS-like polypeptide (12K SS). Native ovine hypothalamic SS-28 was highly potent in inhibiting growth hormone release from cultured rat anterior pituitary cells. The results raised doubts that ovine SS-28 would be an SS precursor, and indicated that SS-28 itself may possess regulatory functions.