Interaction of extended loop 882-892 of Cp with Mpo.

<p>Cp is shown in blue, heavy chain of Mpo in palegreen, light chain of Mpo in pink. Copper ions are shown as orange spheres. Heme is shown in violet, ferrous is shown in gray sphere. (<b>A</b>) Overall view of Cp monomer contact with Mpo monomer. Selected contact is indicated by dash-line oval (<b>B</b>). Zoom of contact area of Cp with the entrance of heme pocket of Mpo. Cp is shown in cartoon; Mpo is shown in cartoon and semi-transparent surface representation. Ends of loop between domain 5 and 6 are marked. <b>(C)</b> Inhibition of ABTS-peroxidase activity of Mpo by synthetic peptide RPYLKVFNPR corresponding to the 883-892 fragment of Cp sequence.</p

Contact areas of Cp with Mpo near 3,4 and 5 domains of Cp.

<p>(<b>A</b>) Contact area near N-terminal of Mpo light-chain and loop 699-720 of Cp. (<b>B</b>) Contact of 699-720 loop of Cp with symmetrical monomer of Mpo. Symmetrical molecule of Cp is not shown for clearance. (<b>C</b>) Contact area near 542-557 and 618-624 loops of Cp. (<b>D</b>) Contact area near <i>p-</i>PD site of Cp (domain 4). Residues M668, W669 and H667 are shown in stick representation.</p

Overall parameters obtained by SAXS.

<p>R_g, D_max and V_p are, respectively, radius of gyration, maximum size and excluded particle volume obtained from experimental SAXS profiles. MM_est is the molecular mass estimated from the excluded volume (using empiric factor of 0.625) and MM_mon is the molecular mass expected from monomeric sequence (or equimolar monomeric assemblies in case of binary and ternary complexes) with glycosylation taken into account. Oligomeric state is defined by the ratio of MM_est to MM_mon. χ is discrepancy between the experimental SAXS data and the curve computed by CRYSOL from the rigid body model of corresponding construct with tentatively added carbohydrates.</p

Data collection statistics and refinement for Cp-Mpo complex and Cp with free labile sites.

*<p>Values in parentheses are for highest resolution shell.</p

Scheme of influence of Cp, Mpo, Lf on functions of each other due to interactions.

<p>Inhibition is shown by thin black arrows, activation or protection of function is shown by bold grey arrows. *Substrates of Mpo: o-DA, 4-chloro-1-naphol, tetramethylbenzidine, ABTS; **Substrates of Cp: <i>o</i>-DA, <i>p</i>-PD, DOPA.</p

Cp-Mpo-Lf in solution.

<p>(<b>A</b>) Scattering patterns of ternary complex and individual proteins. (1): Mpo dimer, (2) Cp with glycans, (3) glycosylated Lf, (4) Monomeric binary complex Cp-Lf and (5) ternary complex. Experimental data are denoted by dots, fits computed from the appropriate portions of the SAXS model are shown as red solid lines. The plots are displaced along the logarithmic scale for better visualization. Insert: Guinier plots (ln I <i>versus</i> s²) with the linear fits (straight lines) in the ranges automatically determined by AutoRg (Petoukhov et al., 2012). (<b>B</b>) SAXS models of the ternary complex. Rigid body model is presented by Ca trace whereby Cp and Lf subunits (two copies each) and Mpo dimer are shown in red, blue and green, respectively. The location of sugars is denoted by appropriately colored solid spheres. Bottom view is rotated by 90 degrees around horizontal axis. <i>Ab initio</i> shapes of the ternary complex (top) reconstructed in P2 and of Cp-Lf (bottom) are shown as grey beads. (<b>C</b>) Zoom of Cp-Lf interaction in ribbon and transparent surface representation. One of possible Lf sugar chain conformation (brown sticks and pink semitransparent surface) is shown in stick and surface representation. Lf-N1 is shown in chocolate, Lf-N2 in yellow, Lf-C1 in pink and Lf-C2 in red. Cp is shown in light cyan. Border of domain 1 is highlighted by blue line. Glycosylation site N119 indicates by black arrow.</p