²H spectra of mechanically oriented 7∶3 POPC-<i>d</i>₃₁:POPG bilayers in the presence (upper panel) and absence (lower panel) of 1 mol% SP-B (1–25,63–78).

<p>The spectra were acquired with 60000 transients at 23°C. Dashed vertical lines indicate the quadrupole splitting of deuterons on the C15 acyl chain segment of POPC-<i>d</i>₃₁ in the absence of SP-B (1–25,63–78).</p

HN region of the ¹H NMR spectra of 1 mM SP-B (1–25,63–78) in SDS micelles at 45°C (red) and 1.5 mM SP-B (8–25,63–78) in SDS micelles at 37°C (blue).

<p>The number of transients was 32. The intensity scale is arbitrary but has been normalized to take into account the differences in peptide concentration.</p

A) Far-UV CD spectra of SP-B (8–25,63–78) (triangles), SP-B (1–25,63–78) (circles) and SP-B (1–7) (squares) dissolved in SDS micelles.

<p>Spectra were taken using a 1 mm path-length quartz cuvette from 200 nm to 260 nm at 25°C. Shown are single scans. Three additional spectra of each sample were acquired and the 4 scans averaged together before % secondary structure was extracted (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072821#pone-0072821-t002" target="_blank"><b>Table 2</b></a>).</p

Partial ¹H chemical shift assignments (in ppm) for residues 1–7 of SP-B, as assigned based on 2D TOCSY and NOESY NMR experiments with SP-B (1–7) and SP-B (1–25,63–78) (Super Mini-B) in deuterated SDS at 45°C.

<p>Note that although three sets of proline resonances were identified, none of them could be identified with a particular proline in the sequence.</p

Splittings, Δ ν, and corresponding order parameters, S_CD, for the resolved peaks of the 2H NMR spectra of POPC-<i>d</i>₃₁/POPG (7∶3) (Figure 1) in the absence and presence of SP-B (1–25,63–78) (Super Mini-B).

<p>The splittings quoted derive from a single experiment; however the uncertainty has been estimated based on the standard deviation in splittings derived from 5 separate control experiments with the same lipid composition.</p

Half ²H NMR spectra of mechanically oriented 7∶3 POPC-<i>d</i>₃₁:POPG bilayers in the absence of peptide (a), in comparison to (b) with 1 mol% SP-B (8–25,63–78) or (c) SP-B (1–25,63–78).

<p>The spectra were all acquired at 23°C. Vertical lines indicate the quadrupole splitting of POPC-<i>d</i>₃₁ deuterons in the absence of peptide.</p

DOSY NMR analysis of SuperMini-B in SDS micelles at 37°C.

<p>DOSY NMR analysis of SuperMini-B in SDS micelles at 37°C.</p

Selected regions of 2D NOESY NMR spectra of 1 mM SP-B (1–25,63–78) in 150 mM SDS solution at pH 5 and 45°C (red) and 1 mM SP-B (8–25,63–78) in 150 mM SDS at pH 5 and 37°C (blue).

<p>Selected regions of 2D NOESY NMR spectra of 1 mM SP-B (1–25,63–78) in 150 mM SDS solution at pH 5 and 45°C (red) and 1 mM SP-B (8–25,63–78) in 150 mM SDS at pH 5 and 37°C (blue).</p

Entry Kinetics of RC-101-Resistant Virus.

<p>Viral entry was observed over one hour to determine differences in entry kinetics between wild type (WT) and RC-101-resistant virus. Equal concentrations of infectious virus were used to infect reporter cells and infection was halted at specific time-points. Entry kinetics is shown as percent of total entry and graphed using cubic splines. Linear regression curves were fit to data and slopes were compared between the 15 and 30-minute time intervals. Error bars represent SEM. Both wild type (WT) and Q66R+N126K had significantly greater slopes than the Q66R mutant (N = 4; <i>p</i><0.05).</p

Spectroscopic behavior of Mini-B and DEPN-8.

<p><u>Panel A</u>: CD spectrum for Mini-B in trifluoroethanol (TFE); <u>Panel B</u>: FTIR spectrum for DEPN-8; <u>Panel C</u>: FTIR spectral differences for Mini-B in DEPN-8 (dashed line) compared to Mini-B in TFE (solid line). In Panel A, mean residue ellipticity (MRE) averaged over eight scans is plotted against wavelength for Mini-B in 4∶6 (v:v) TFE:10 mM phosphate buffer, pH 7.4. The double minimum at ∼208 and 222 nm is indicative of a high α-helical content. In Panel B, the spectrum for DEPN-8 multilayers (100 µg lipid, arbitrary absorbance units) has a “C-O-C” ether linkage-associated absorption band centered at a wavenumber of 1072 cm⁻¹. In Panel C, the IR spectrum of Mini-B in TFE (solid line) has a peak at 1655 cm⁻¹ indicating high α-helix levels, while the peak at 1658 cm⁻¹ and high-field shoulder at 1678 cm⁻¹ for Mini-B in DEPN-8 (dashed line) indicates an increase in turn/bend conformation with a decreased but still prominent α-helix content. See text for discussion.</p