Synthesis of a putative subtype specific antigenic heptapeptide from Escherichia coli K88 ad protein fimbriae.
The heptapeptide methyl ester Phe-Asn-Glu-Asn-Met-Ala-Tyr-OMe covering the amino acid sequence of the region 213-219 of Escherichia Coli K88 ad protein fimbriae is synthesized using N alpha-t-butyloxycarbonyl-protection and benzyl groups for side-chain-protection. All condensation reactions are performed in 84-97% yield by preactivation of the protected amino acids by dicyclohexylcarbodiimide (DCC) and 1-hydroxybenzotriazole (HOBt), and reaction of the resulting active ester with amine in the presence of 4-methylmorpholine (NMM). A mechanism is proposed for the nitrile formation in the side-chain of activated asparagine, and the suppression of this side-reaction is investigated. The repetitive deprotection is performed in a mixture of trifluoroacetic acid (TFA), phenol and p-cresol to give the TFA salts in virtually quantitatively yields. The final deprotection of the heptapeptide is carried out in a mixture of 25% hydrogen fluoride (HF) and dimethyl sulfide (DMS) in an overall yield of 48%. The serological and conformational properties of the synthetic peptide are under investigation.
Meldal
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D000942:Antigens, Bacterial; D004926:Escherichia coli / Q000276:immunology*; D010861:Fimbriae, Bacterial / Q000276:immunology*; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D009842:Oligopeptides / Q000138:chemical synthesis*; D009904:Optical Rotation; D013045:Species Specificity
D000942:Antigens, Bacterial; D007202:Indicators and Reagents; D009842:Oligopeptides