The synthesis of the heptacosapeptide amide with the primary structure of Human-secretin is described. For this purpose 7 fragments were designed, i.e. H-Gly-Leu-Val-NH2 [25-27b], Z-Arg(Z2)-Leu-Leu-Gln-OH [21-24], Z-Arg(Z2)-Leu-Gln-OH[18-20], Z-Arg(Z2)-Glu(OtBu)-Gly-Ala-OH [14-17], Z-Arg(Z2)-Leu-OH [12-13], Z-Thr(tBu)-Ser(tBu)-Glu(OtBu)-Leu-Ser(tBu)-OH [7-11], Adoc-His(Adoc)-Ser(tBu)-Asp(OtBu)-Gly-Thr(tBu)-Phe-OH [1-6]; these fragments were consequently assembled to the overall protected total sequence using the Wunsch/Weygand-method with dicyclohexylcarbodiimide. After deprotection by exposure to trifluoroacetic acid in presence of 1,2-ethanedithiol and water as scavenger, the isolated crude product was purified by column chromatography on CM-Sepharose, fast flow. This synthetized Human-secretin showed the full biological activity in comparison to Porcine-secretin.
Direct PCR amplification of various modified DNAs having amino acids: Convenient preparation of DNA libraries with high-potential activities for in vitro selection
摘要:
We synthesized modified 2'-deoxyuridine triphosphates bearing amino acids at the C5 position and investigated their substrate properties for KOD Dash DNA polymerase during polymerase chain reaction (PCR). PCR using C5-modified dUTP having an amino acyl group (arginyl, histidyl, lysyl, phenylalanyl, tryptophanyl, leucyl, prolyl, glutaminyl, seryl, O-benzyl seryl or threonyl group) gave the corresponding full-length PCR products in good yield. Although dUTP analogues bearing aspartyl, glutamyl or cysteinyl were found to be poor substrates for PCR catalyzed by KOD Dash DNA polymerase, optimization of the reaction conditions resulted in substantial generation of full-length product. In the case of reaction using dUTP analogue having a cysteinyl group, addition of a reducing agent improved the reaction yield. Thus, PCRs using KOD Dash DNA polymerase together with amino acyl dUTP provide convenient and efficient preparation of various modified DNA libraries with potential protein-like activities. (c) 2005 Elsevier Ltd. All rights reserved.
Design and synthesis of peptide derivatives of a 3-deoxy-D-manno-2-octulosonic acid (KDO) analog as novel antibacterial agents acting upon lipopolysaccharide biosynthesis
作者:Alf Claesson、Anita M. Jansson、Brian G. Pring、Stephen M. Hammond、Bertil Ekstroem
DOI:10.1021/jm00395a022
日期:1987.12
cytidylyltransferase, attempts were made to design derivatives that would act as antibacterials against Gram-negative bacteria by inhibiting lipopolysaccharide biosynthesis. Compound 3 and the derivatives 15 and 16 containing an additional amino acid were not lethal to bacteria. However, compounds 17-22, which contain a N-terminally linked dipeptide, exhibited good antibacterial activity in vitro on testing against