Fig. 7.

Characterization of tricyclic Covcore protein 3H2. (A) 3H2 sequence. Underlined residues are the cross-linking sites. (B) CD spectra of linear precursor 3H2-1, backbone cyclized precursors 3H2-2, tricyclic 3H2, and side chain cross-linked 3H2-3. Unit for mean residue ellipticity (MRE) is 10³ deg cm² dmol⁻¹. (C) Analytical HPLC and mass spectrometry analysis of 3H2, Mass: Obsd. 6,280.4 ± 0.5 Da, Calc. 6,280.2 Da (average isotope composition). (D) Representative electron density maps of the amide bond between Gly1and Ser60. (E) The electron density maps of the covalent core. σA-weighted 2Fo − Fc electron density map at a σ level of 1.