FIGURE 4.

Hb peptides used for empirical validations. A, designations and sequences of the Hb peptides. Nine peptides were designed to incorporate the putative LPS-binding residues (underlined in the sequence). The peptides are designated A and B corresponding to the Hb α and β subunits, respectively. Two additional control peptides were (i) A111, composed of the stretch of residues which were predicted to be non-LPS binding, and (ii) B59sm, mutant peptide obtained by replacing the predicted LPS-binding residues of B59s with aspartic acid. B, mapping of the Hb peptides on the tetrameric structure. Tetrameric Hb showing the peptides designed to incorporate the predicted LPS-binding sites. The α subunits are colored gold, and the β subunits are colored violet. The heme moiety is represented by sticks, whereas the polypeptide chains are shown as ribbons. The peptides are labeled for chains A and B. C, secondary structure of Hb peptides. Far-UV CD spectra of Hb peptides in PBS, pH 7.4, at 298 K. Peptide concentration was 40 μm. A negative peak near 200 nm represents a random coil structure. Panel I, α subunit peptides: A1 (green), A16 (blue), A56 (red), A81 (aqua), A131 (brown), A111 (cyan); and panel II, β subunit peptides: B1 (green), B59 (aqua), B59s (red), B139 (blue), B59sm (black).