The usefulness of a new deprotecting procedure was demonstrated in the solution syntheses of two porcine spinal cord peptides, designated neuromedin U-8 and neuromedin U-25. Protected neuromedin U-8 (8-residue peptide), prepared by condensation of two fragments, served as a C-terminal amino component for the synthesis of neuromedin U-25 (25-residue peptide). Onto this fragment, five peptide fragments were successively condensed by the azide procedure to construct the entire amino acid sequence of neuromedin U-25, a possible biosynthetic precursor of neuromedin U-8. All protecting groups were cleaved from protected neuromedin U-8 and neuromedin U-25 by 1 M trimethylsilyl trifluoromethanesulfonate-thioanisole in trifluoroacetic acid. The results were compared with those obtained by trifluoromethanesulfonic acid deprotection. In terms of contractile activity in rat uterus, neuromedin U-25 was twice as active as neuromedin U-8.
在溶液合成两种猪脊髓
多肽(分别为神经生长因子 U-8 和神经生长因子 U-25)的过程中,证明了新的去保护程序的实用性。通过缩合两个片段制备的受保护神经生长素 U-8(8 个残基的
多肽)可作为合成神经生长素 U-25(25 个残基的
多肽)的 C 端
氨基成分。在这一片段上,用
叠氮程序连续缩合了五个肽片段,从而构建了神经生长素 U-25 的整个
氨基酸序列,它可能是神经生长素 U-8 的
生物合成前体。在
三氟乙酸中用 1 M 三甲基
硅基
三氟甲磺酸-
硫代
苯甲醚裂解了受保护的神经生长素 U-8 和神经生长素 U-25 上的所有保护基团。结果与
三氟甲磺酸脱保护法的结果进行了比较。在大鼠子宫收缩活性方面,神经生长素 U-25 是神经生长素 U-8 的两倍。