A detailed analysis of backbone amide NH chemical shift temperature gradients (∆δ/∆T values) for proteins and highly cross-linked peptides reveals that hydrogen-bonded exchange-protected NHs are characterized by ∆δ/∆T values of -2.0 ( 1.4 ppb/°C while exposed NHs typically display gradients of -6.0 f -8.5 ppb/°C; however, numerous exceptions to these generalizations occur. For partially folded peptides (rather than proteins), exceptions are more common than concordance with this rule; ∆δ/∆T values ranging from -28 to +12 ppb/°C have been observed. In the case of the peptide systems for which exchange protection data is available, the common practice of assuming that a ∆δ/∆T value less negative than -4 ppb/°C indicates that the NH is sequestered from solvent is shown to have zero predictive validity. The analysis of the data for partially folded peptides, protein fragments, and other peptides which are expected to display minimal structuring reveals a significant correlation between ∆δ/∆T and the deviation of δ NH from the random coil reference shift. The analysis was facilitated by plotting NH chemical shift deviations (NH-CSD) Versus the ∆δ/∆T values. Using such plots, slow-exchanging hydrogen-bonded sites in proteins can be determined with much higher confidence than using the value of the gradient alone. For peptides, the occurrence of large shift deviations and abnormal gradients are diagnostic for partial structuring at lower temperatures which becomes increasingly randomized on warming. A good correlation coefficient (R g 0.75) for NH-CSD and ∆δ/∆T values indicates that essentially all of the NH shift deviation from reference values is due to the concerted formation of a single structured state on cooling. Correlation coefficients greater than 0.95 were observed for both helix and -hairpin forming peptides. The slope of the correlation plot (parts per thousand/°C) is a measure of the decrease in the population of the structured state upon warming. A detailed model which rationalizes the effects of conformational equilibria upon NH shifts is presented. A positive ∆Cp for unfolding is required to rationalize the linearity of δ NH with temperature that is routinely observed for partially structured peptides. This analysis suggests that ordered states of short peptides achieve significant populations in water only when the hydrophobic effect favors the structured state. This conclusion is pertinent to the current questions concerning the temporal sequence of secondary Versus tertiary structure formation during protein folding. Further, it is suggested that the use of NMR parameters (scalar and dipolar couplings) to derive the structural preferences of protein fragments which might serve a "seeding" role in the folding pathway is justified only when the CSD/gradient plot displays both a correlation coefficient greater than 0.70 and significant NH-CSD values (|CSD| > 0.3).With the development of 2D NMR methods, peptide/protein structure elucidation has been dominated by methods based on NOE-derived distance const...

Greater than 90% of lung infections in cystic fibrosis (CF) patients are caused by Pseudomonas aeruginosa, and the majority of these patients subsequently die from lung damage. Current therapies are either targeted at reducing obstruction, reducing inflammation, or reducing infection. To identify potential therapeutic agents for the CF lung, 150 antimicrobial peptides consisting of three distinct structural classes were screened against mucoid and multidrug-resistant clinical isolates of P. aeruginosa, Stenotrophomonas maltophilia, Achromobacter xylosoxidans, and Staphylococcus aureus. Five peptides that retained potent antimicrobial activities in physiological salt and divalent cation environment were further characterized in vivo using a rat chronic lung infection model. All animals were inoculated intratracheally with 10 4 P. aeruginosa mucoid PAO1 cells in agar beads. Three days following inoculation treatment was initiated. Animals were treated daily for 3 days with 100 l of peptide solution (1 mg/ml) in 10 mM sodium citrate, which was deposited via either intratracheal instillation or aerosolization. Control animals received daily exposure to vehicle alone. At the end of the treatment the lungs of the animals were removed for quantitative culture. Four peptides, HBCM2, HBCM3, HBCP␣-2, and HB71, demonstrated significant reduction in Pseudomonas bioburden in the lung of rats. Further in vivo studies provided direct evidence that anti-inflammatory activity was associated with three of these peptides. Therefore, small bioactive peptides have the potential to attack two of the components responsible for the progression of lung damage in the CF disease: infection and inflammation.

The persistence of pain after surgery increases the recovery interval from surgery to a normal quality of life. AYX1 is a DNA-decoy drug candidate designed to prevent post-surgical pain following a single intrathecal injection. Tissue injury causes a transient activation of the transcription factor EGR1 in the dorsal root ganglia-dorsal horn network, which then triggers changes in gene expression that induce neuronal hypersensitivity. AYX1 is a potent, specific inhibitor of EGR1 activity that mimics the genomic EGR1-binding sequence. Administered in the peri-operative period, AYX1 dose dependently prevents mechanical hypersensitivity in models of acute incisional (plantar), inflammatory (CFA), and chronic neuropathic pain (SNI) in rats. Furthermore, in a knee surgery model evaluating functional measures of postoperative pain, AYX1 improved weight-bearing incapacitance and spontaneous rearing compared to control. These data illustrate the potential clinical therapeutic benefits of AYX1 for preventing the transition of acute to chronic post-surgical pain.

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Antimicrobial peptides are essential to innate host defense as effectors of pathogen clearance and can modify host cell behaviors to promote wound repair. While these two functions appear interrelated, it is unclear whether the ability to aid in wound repair requires inherent antimicrobial function. We hypothesized that the influence of antimicrobial peptides on wound repair is not dependent on antimicrobial function. To explore this, we analyzed the microbial killing activity of peptide fragments and correlated this with the ability to influence wound repair in mice. HB-107, a peptide lacking antimicrobial activity and originally derived from the antimicrobial cecropin B, showed up to 64 percent improvement in wound repair compared to scrambled peptide and vehicle controls, an effect comparable to treatment with recombinant human platelet-derived growth factor-BB (formulated as Regranex). Wounds treated with HB-107 showed keratinocyte hyperplasia and increased leukocyte infiltration. Furthermore, HB-107 stimulated interleukin-8 secretion from cultured endothelial cells, an effect that may explain the increase in leukocyte migration. These findings confirm that antimicrobial peptides can function as effectors of cutaneous wound repair. Moreover, this study furthers our understanding of antimicrobial peptides by showing that their wound repair properties can be independent of antimicrobial function.