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DSIP and its fourteen analogs as well as three short peptides were synthesized by solid phasemethod. Thed1esign of the analogs was based on the consideration of the introduction of D-aminoacid into the molecules to inhibit the enzymatic hydrolysis and the introduction of amino acids witha hydrophobic side chain. The modification was placed on the position of 1,3,4,5,8 and 9,e.g.D-Trp~1,Tyr~1,Tyr~1 Phe~5,D-Trp~1 Phe~8,Trp~(3,4), D-Trp~(1,3,4)Phe8, D-Trp~(3,4)phe~8 D-Glu~9,D-pF-Phe~(3,4)Phe~8 D-Glu~9, Phe~5,Glu~5 Asp~9,Tyr~5 Asp~9,Asp~9 and Ala~7-DSIP as well as Trp-Ala-Gly-Gly-Asp,Trp-Ala-Gly-Gly-Glu and Trp-Gly-Glu. DSIP and Phe~5-DSIP were also prepared by pentafluo-rophenyl ester method. The purity of the synthetic peptides was checked by amino acid analysis.elemental analysis, thin layer chromatography and paper electrophoresis. The biological assay showedthat the analogs of D-Trp~1,Tyr~1,Tyr~1 Phe~5 and Ala~7-DSIP as well as three short peptides wereinactive whereas Phe~5-DSIP showed similar activity as that of synthetic DSIP.
DSIP and its fourteen analogs as well as three short peptides were synthesized by solid phase method. The work of the analogs was based on the consideration of the introduction of D-aminoacid into the molecules to inhibit the enzymatic hydrolysis and the introduction of amino acids witha hydrophobic side chain. The modification was placed on the position of 1,3,4,5,8 and 9, egD-Trp ~ 1, Tyr ~ 1, Tyr ~ 1 Phe ~ 5, D-Trp ~ (3,4), D-Trp ~ (1,3,4) Phe8, D-Trp ~ (3,4) phe ~ 8 D-Glu ~ 9, D-pF-Phe ~ 8 D-Glu ~ 9, Phe ~ 5, Glu ~ 5 Asp ~ 9, Tyr ~ 5 Asp ~ 9, Asp ~ 9 and Ala ~ 7-DSIP as well as Trp-Ala-Gly- Gly-Asp, Trp-Ala Gly-Glu and Trp-Gly-Glu. DSIP and Phe ~ 5-DSIP were also prepared by pentafluo-rophenyl ester method. The purity of the synthetic peptides was checked by amino acid analysis. Elementary analysis, thin layer chromatography and Paper electrophoresis. The biological assay showed that the analogs of D-Trp ~ 1, Tyr ~ 1, Tyr ~ 1 Phe ~ 5 and Ala ~ 7-DSIP as well as three short peptides were active in Phe ~ 5-DSIP show ed similar activity as that of synthetic DSIP.