The Complete Amino‐Acid Sequence of the K88 Antigen, a Fimbrial Protein from Escherichia coli

The complete primary structure of the fimbrial protein of the K88 antigen has been elucidated. This protein, which makes up the building block for the macromolecular structure that comprises a fimbria, consists of 264 amino acid residues in a single polypeptide chain. The K88 antigen was fragmented by chemical cleavage with cyanogen bromide, and by subsequent enzymatic sub-cleavage of resulting fragments with trypsin and chymotrypsin, and was additionally cleaved with o-iodosobenzoic acid. Peptides were sequenced by manual Edman degradation. The carboxy-terminal part of the molecular is remarkable in being almost devoid of charged amino acid residues and is highly hydrophobic. Furthermore, this part of the structure could have a specific function as molecular anchor.