Morphology and structural properties of pH-responsive amphiphilic peptides.
Protein nanomaterials at the peptide level have shown great potential for medical applications. Peptides change their morphological conformation because of changes in self-assembly properties when they are exposed to changes in solvent composition or pH. Two 15-residue peptide sequences, KhK (KKKFLIVIGSIIKKK) and Alternating Kh (KFLKKIVKIGKKSII), were designed for the purpose of determining the role of peptide sequence on solution morphology and conformation. KhK solutions exhibited a random coil to helical transition when solvent conditions were changed from water to a trifluorethanol/water solution at acidic pH. Alternating Kh solutions, however, demonstrated primarily random coil character under similar solvent and pH conditions as determined by circular dichroism spectroscopy and 2D-1H-1H nuclear magnetic resonance spectroscopy. At basic pH, circular dichroism spectroscopy and nuclear magnetic resonance spectroscopy analysis demonstrated that random coil character increased at basic pH for KhK, whereas Alternating Kh exhibited an increase in beta-sheet character. Further analysis by transmission electron microscopy showed marked differences in the peptide solution morphology. Peptide particle aggregation and fiber formation were significantly affected by solvent composition and pH values for both peptide sequences.
Bio-Materials and Technology Lab, Department of Grain Science and Industry, Manhattan, Kansas 66506, USA.
Jeanne N
JN
Shera
Daisuke
D
Takahashi
Alvaro I
AI
Herrera
Om
O
Prakash
Xiuzhi Susan
XS
Sun
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D008969:Molecular Sequence Data; D049329:Nanostructures; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation
D010455:Peptides