Solution structure of a novel D-naphthylalanine substituted peptide with potential antibacterial and antifungal activities.
A new type of Trp-rich peptide, Ac-KWRRWVRWI-NH2, designated as Pac-525, was found to possess improved activity against both gram-positive and negative bacteria. We have synthesized two Pac-525 analogues, D-Pac-525 containing all D-amino acids and D-Nal-Pac-525, the D-Pac-525 analogue with tryptophan replaced by D-beta-naphthylalanine. We have determined the solution structure of D-Nal-Pac-525 bound to membrane-mimetic DPC micelles by two-dimensional NMR methods. The DPC micelle-bound structure of D-Nal-Pac-525 adopts a left-hand alpha-helical segment and the positively charged residues are clustered together to form a hydrophilic patch. The surface electrostatic potential map indicates the three D-beta-naphthylalanines are packed against the peptide backbone and form an amphipathic structure. A variety of biophysical and biochemical experiments, including circular dichroism, fluorescence spectroscopy, and microcalorimetry, were used to show that D-Nal-Pac-525 interacted strongly with negatively charged phospholipid vesicles and induced efficient dye release from these vesicles, suggesting that the strong antimicrobial activity of D-Nal-Pac-525 may be due to interactions with bacterial and fungus membranes.
Wu
Jiun-Ming
JM
Institute of Biotechnology and Department of Life Science, National Tsing Hua University, Hsinchu 300, Taiwan.
Wei
Shu-Yi
SY
Chen
Heng-Li
HL
Weng
Kuo-Yao
KY
Cheng
Hsi-Tsung
HT
Cheng
Jya-Wei
JW
D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D000935:Antifungal Agents / Q000737:chemistry* / Q000494:pharmacology*; D002151:Calorimetry; D002176:Candida albicans / Q000187:drug effects; D002942:Circular Dichroism; D005452:Fluoresceins / Q000737:chemistry; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*; D011489:Protein Denaturation; D013050:Spectrometry, Fluorescence; D013696:Temperature; D017186:Titrimetry; D014364:Tryptophan / Q000737:chemistry; D015091:beta-Alanine / Q000031:analogs & derivatives* / Q000737:chemistry
D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D005452:Fluoresceins; D010455:Peptides; D015091:beta-Alanine; C063914:beta-naphthylalanine; D014364:Tryptophan; C007740:fluorexon