개량된 반응기구를 사용하여 고상법으로 methionine enkephalin 및 ($Phe^1$), (D-$Ala^1$), (D-$Ala^2$) enkephalin을 합성하였으며 이들의 수득율은 55~65%였다. Coupling은 dicyclohexycarbodimide에 의하여 이루어 졌으며 HBr으로 Cleavage한 각 펩티드는 gel filteration 및 ion-exchange chromatography에 의해 분리하였고 이들의 순도 결정은 thin layer chromatography, paper chromatography, paper electrophoresis, melting point 및 아미노분석에 의거 하였다. Methionine enkephalin 및 ($Phe^1$), (D-$Ala^1$), (D-$Ala^2$) enkephalin을 in-vitro 상에서 endopeptidase ($alpha$-chymotrypsin, trypsin) 과 exopeptidase (carboxypeptidase, leucineaminopeptidase)를 사용하여 이들의 분해 실험을 했다. $alpha$-chymotrypsin, carboxypeptidase 및 leucine aminopeptidase는 peptide를 빠르게 분해 시켰으나 trypsin의 작용은 받지 않았다.
Synthesis of methionine enkephalin and ($phe^1$), (D-$ala^1$), (D-$ala^2$) analogues of methionine enkephalin was carried by solid phase method. The yield ranged from 55 to 65% owing to an improved reaction vessel. Coupling was performed by dicyclohexylcarbodiimide. After cleavage with dried HBr, the peptides were purified by gel filtration and ion-exchange chromatography. Their purity was assessed by thin layer chromatography, paper electrophoresis, melting point and amino acid analysis. Methionine enkephalin and ($phe^1$), (D-$ala^1$), (D-$ala^2$) analogues of methione enkephalin were incubated in vitro with endopeptidase ($alpha$-chymotrypsin, trypsin) and exopeptidase (carboxypeptidase A, leucine aminopeptidase) in order to study the degradation patterns of peptides. Methionine enkephalin and ($phe^1$), (D-$ala^1$), (D-$ala^2$) analogues of methionine enkephalin were rapidly degradated by $alpha$-chymotrypsin, carboxypeptidase A and leucine aminopeptidase and therefore they were not attacked by trypsin.
