van Hofsten P, Faye I, Kockum K, Lee J Y, Xanthopoulos K G, Boman I A, Boman H G, Engström A, Andreu D, Merrifield R B
Proc Natl Acad Sci U S A. 1985 Apr;82(8):2240-3. doi: 10.1073/pnas.82.8.2240.
Two cDNA clones containing coding information for cecropin B from the Cecropia moth (Hyalophora cecropia) were identified by means of a synthetic probe. Sequencing of the two inserts showed that cecropin B is processed from a 62-amino acid residue precursor molecule including a 26-residue leader peptide and a COOH-terminal glycine residue. The latter presumably donates the nitrogen of the amide group present on the COOH-terminal leucine residue of the mature cecropin B. The sequence deduced for the mature cecropin B differed in the COOH-terminal region from the tentative structure previously determined by carboxypeptidase digestion. To settle the discrepancy, cecropin B was synthesized according to the cDNA sequence with an amidated COOH-terminal leucine. Natural and synthetic cecropin B were found to be indistinguishable with respect to electrophoretic mobility and antibacterial activity against seven different bacteria. The COOH-terminal tetrapeptides were isolated from both natural and synthetic cecropin B and found to be indistinguishable. The correct sequence for cecropin B is (formula; see text).
通过合成探针鉴定出两个含有天蚕蛾（大透目天蚕蛾）天蚕素B编码信息的cDNA克隆。对这两个插入片段的测序表明，天蚕素B是由一个62个氨基酸残基的前体分子加工而来，该前体分子包括一个26个残基的前导肽和一个COOH末端甘氨酸残基。后者可能为成熟天蚕素B的COOH末端亮氨酸残基上存在的酰胺基团提供氮原子。推导的成熟天蚕素B序列在COOH末端区域与先前通过羧肽酶消化确定的暂定结构不同。为了解决这一差异，根据具有酰胺化COOH末端亮氨酸的cDNA序列合成了天蚕素B。发现天然和合成的天蚕素B在电泳迁移率和对七种不同细菌的抗菌活性方面无法区分。从天然和合成的天蚕素B中分离出COOH末端四肽，发现它们无法区分。天蚕素B的正确序列为（分子式；见正文）。
