Pseudomonas aeruginosa and Burkholderia cepacia produce metalloproteases that effect lung injury. Two epitopes (peptides 15 and 42) previously identified on P. aeruginosa elastase induce the production of antibodies that neutralize protease activity. The effects of immunization with synthetic peptides based on these epitopes on experimental lung infections due to P. aeruginosa or B. cepacia were examined. Rats were immunized with peptides conjugated to keyhole limpet hemocyanin or tetanus toxoid before infection. Immunization with peptide 15 (pep15) resulted in a decrease in total cells and polymorphonuclear leukocytes in bronchoalveolar lavage (BAL) fluid and a 50%-70% decrease in lung histopathologic changes, compared with findings in controls. Immunization with peptide 42 decreased cells in BAL fluid but did not decrease lung pathologic changes. Immunization with pep15 alone was just as effective in protecting against lung injury as immunization with a combination of both peptides. These studies suggest that immunization with pep15 can reduce the severity of lung infections due to P. aeruginosa or B. cepacia.

Amino acid analyses of tropomyosin have previously shown four histidine and 13–14 methionine residues per mole (70 000 daltons) of tropomyosin. The isolation of two unique histidyl and five unique methionyl sequences is described. The number of unique methionyl peptides will undoubtedly be increased when more extensive sequence information becomes available although the value of 2 for the unique histidine sequences is considered to be a maximal one. These data support the conclusion that the two subunits of tropomyosin are similar in amino acid sequence. Both the acetylated NH2-terminal and COOH-terminal sequences of the protein have been determined in this study. The isolation and sequence analysis of two varieties of peptides arising from the COOH-terminus of the protein indicates either a degree of proteolysis during its isolation or a difference in the constituent polypeptide chains of tropomyosin in this region of their structures. The limited sequences reported indicate a repeat of hydrophobic residues as required by the inter-chain packing of a coiled-coil structure.

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Amino acid analyses of tropomyosin have shown three cysteine residues per mole (M.W. 70 000) of tropomyosin. The cysteine content was determined by cysteic acid determinations, incorporation of 14C-labelled iodoacetic acid into the protein, and the analysis of S-carboxymethylcysteine after acid hydrolysis. The isolation of three unique cysteinyl peptides is incompatible with a homogeneous tropomyosin preparation of two chemically identical subunits. The amino acid sequences reported in this study indicate a regular repeat of hydrophobic residues as required by the inter-chain packing of a coiled-coil structure.