Kaljuste K, Undén A
Department of Neurochemistry and Neurotoxicology, Stockholm University, Sweden.
Int J Pept Protein Res. 1994 May;43(5):505-11. doi: 10.1111/j.1399-3011.1994.tb00550.x.
A model peptide with the sequences Ala-Pro-Lys(2ClZ)-Tyr(2BrZ) was synthesized on a 4-methylbenzhydryl amine (MBHA) polystyrene resin using conventional Boc/benzyl protective group strategy. The amino acid aldehyde Boc-valinal was coupled by reductive alkylation with NaCNBH3 in acidified DMF for 1 h. The secondary amine in the peptide-resin Boc-Val psi[CH2NH]Ala-Pro-Lys(2ClZ)-Tyr(2BrZ)-MBHA was reductively alkylated by 3(4-methylbenzylthio)-propanal at 40 degrees C for 6 h, resulting the peptide-resin Boc-Val psi[CH2N(CH2CH2CH2-S-pMeBzl)]Ala-Pro-Lys(2ClZ)-T yr(2BrZ)-MBHA. After the removal of the Boc group the synthesis was continued employing the above-mentioned methods, which led to the resin-bound peptide Leu psi[CH2N(CH2CH2CH2S-pMeBzl)]Ser-Pro-Gly-Lys(2ClZ )-Val psi [CH2N(CH2CH2CH2-S-pMeBzl)]Ala-Pro-Lys(2ClZ)-Tyr( 2BrZ)-MBHA. The peptide was cleaved from the resin with hydrogen fluoride. Reversed-phase HPLC and plasma desorbtion mass spectrometry analysis showed that the expected peptide Leu psi[CH2N(CH2CH2CH2SH)]Ser-Pro-Gly-Lys-Val psi[CH2N(CH2CH2CH2-SH)] Ala-Pro-Lys-Tyr-NH2 was obtained as the major product with low levels of side products. Intramolecular oxidation of the thiols gave the backbone to backbone cyclized peptide Leu psi[CH2N(CH2CH2CH2S)]Ser-Pro-Gly-Lys- Val psi[CH2N(CH2CH2CH2-S)]Ala-Pro-Lys-Tyr-NH2.
采用传统的Boc/苄基保护基策略，在4-甲基二苯甲基胺（MBHA）聚苯乙烯树脂上合成了序列为Ala-Pro-Lys(2ClZ)-Tyr(2BrZ)的模型肽。氨基酸醛Boc-缬氨酸醛在酸化的N,N-二甲基甲酰胺（DMF）中与氰基硼氢化钠通过还原烷基化反应偶联1小时。肽树脂Boc-Val psi[CH2NH]Ala-Pro-Lys(2ClZ)-Tyr(2BrZ)-MBHA中的仲胺在40℃下与3-(4-甲基苄硫基)丙醛通过还原烷基化反应反应6小时，得到肽树脂Boc-Val psi[CH2N(CH2CH2CH2-S-pMeBzl)]Ala-Pro-Lys(2ClZ)-Tyr(2BrZ)-MBHA。脱除Boc保护基后，继续采用上述方法进行合成，得到树脂结合肽Leu psi[CH2N(CH2CH2CH2S-pMeBzl)]Ser-Pro-Gly-Lys(2ClZ)-Val psi [CH2N(CH2CH2CH2-S-pMeBzl)]Ala-Pro-Lys(2ClZ)-Tyr(2BrZ)-MBHA。用氟化氢将肽从树脂上裂解下来。反相高效液相色谱（HPLC）和等离子体解吸质谱分析表明，得到了预期的肽Leu psi[CH2N(CH2CH2CH2SH)]Ser-Pro-Gly-Lys-Val psi[CH2N(CH2CH2CH2-SH)]Ala-Pro-Lys-Tyr-NH2作为主要产物，副产物含量较低。硫醇的分子内氧化得到了主链到主链环化的肽Leu psi[CH2N(CH2CH2CH2S)]Ser-Pro-Gly-Lys-Val psi[CH2N(CH2CH2CH2-S)]Ala-Pro-Lys-Tyr-NH2。
