Critical micelle concentration assessed via fluorescence spectroscopy.

<p>As an example, pyrene fluorescence excitation spectra are shown for a concentration sequence of Adec8 in (A). The formation of micelles is monitored via partitioning of pyrene into the hydrophobic cavity of the forming micelles. This induces the observed peak-shift of pyrene (A), which is quantified via the intensity ratio R = I₃₃₉/I₃₃₃ plotted in (B) as a function of peptide concentration. In the current work, the cmc is defined as the point where R deviates from the background signal.</p

Partitioning of MPX, Ala1 and Ala14 onto POPC∶POPG (3∶1) LUVs studied via ITC at 37°C.

<p>In panel (A), heat traces of 25 mM LUVs injected into 20 µM peptide (19×2 µL injections) are shown. Panel (B) shows the corresponding heat of reaction, Q, as a function of number of injections. The solid lines in (B) represent fits to the data. In panel C, the change in potency of Ala1 and Ala14 for neutral or anionic lipid membranes measured relative to MPX, is evaluated via the ratio <i>K_ins</i>/<i>K_ins(MPX)</i> and <i>K_eff/K_eff(MPX)</i> respectively. The membrane charge selectivity of the peptide (ability to select between neutral and anionic lipid membranes) is assessed via the partitioning coefficient ratio <i>K_eff/K_ins</i> shown in (C).</p

Structures of MPX and eight analogues.

<p>Ala1 and Ala14 have alanine substitution at position 1 or 14, and are analogues with reduced hydrophobicity. Leu8 has a leucine substitution in position 8 resulting in augmented hydrophobicity. Adec1, Adec8 and Adec14 have 2-amino-decanoic acid substitution in position 1, 8 or 14 respectively, and constitute the most hydrophobic analogues of MPX considered in this study. PAMPX and OAMPX are N^α-terminal propanoic and octanoic acid acyl analogues of MPX, respectively.</p

Compilation of results.

<p>Critical micelle concentration (<i>cmc</i> in µM units), effective charge (<i>z_eff</i>) of the peptide, partition coefficient of insertion (<i>K_ins</i>), effective partition coefficient (<i>K_eff</i>), molar enthalpy of partitioning ( in kJ/mol units), minimal inhibitory concentration (<i>MIC</i> in µM units) and the haemolytic potency is given as the concentration <i>H5</i> (in µM units) at which 5% haemolysis has been obtained. Membrane partitioning data for PAMPX, Leu8, Adec1, Adec8, Adec14 and OAMPX could not be analysed and these cells are marked with a dashed line.</p

Mode of peptide-membrane interaction evaluated using ITC at 37°C.

<p>Panel A–C shows the heat trace of 20 mM POPC∶POPG (3∶1) LUVs injected into 100 µM peptide (38×1 µL injections), except for OAMPX which was titrated using 8 mM LUVs. The corresponding heat of reaction (Q) and accumulated heat of reaction (Q_acc) are shown in panel D–F and G–I respectively. The arrows in panel D–F highlight the endpoint of the secondary process and the solid lines serve to guide the eye.</p

Bactericidal potency of MPX and analogues.

<p>The degree of red blood cell haemolysis is plotted as a function of peptide concentration.</p

Additional file 1: of Changes in Lolium perenne transcriptome during cold acclimation in two genotypes adapted to different climatic conditions

Heat maps derived from hierarchical clustering of transcripts differentially expressed in ‘Veyo’ and ‘Falster’ during cold acclimation. Expression patterns across d 0, 9, 13, and 17 of cold acclimation in (A) ‘Veyo’ and (B) ‘Falster’. Green represents up-regulation, and red represents down-regulation. (TIFF 494 kb