title: A novel assay to probe heparin-peptide interactions using pentapeptide-stabilized gold nanoparticles.
abstract: In this article, we present a novel assay to probe the interactions between heparin and heparin-binding peptides based on CALNN pentapeptide-stabilized gold nanoparticles. This assay relies on rapid aggregation of gold nanoparticles and dramatic retardation in the presence of a large excess of heparin due to the binding of peptides to heparin. Using this method, the dissociation constant ( K d) and melting temperature ( T m) of three different peptides against heparin were determined. The results from capillary electrophoresis demonstrated that K d values measured by this method were comparatively accurate. It was found that the peptide with the lowest K d did not have the highest T m. Structural analysis by circular dichroism was performed to explain this phenomenon. A comparison with the results from affinity chromatography indicates that electrostatic interactions only are not the major determinant of the affinity between heparin and peptide, but other interactions such as hydrogen-bonding and hydrophobic interactions may play important roles in the overall interactions. This novel assay is inexpensive, label-free, and easy to implement in the laboratories, does not suffer precipitation of the heparin-peptide complex or their conformational changes caused by surface immobilization, and is expected to be a useful complement to other existing methods.
authors.affiliation: School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907-2032, USA.
authors.forename: Kyung Jae
authors.initials: KJ
authors.lastname: Jeong
authors.forename: Karen
authors.initials: K
authors.lastname: Butterfield
authors.forename: Alyssa
authors.initials: A
authors.lastname: Panitch
mesh_terms: D000595:Amino Acid Sequence; D002138:Calibration; D002942:Circular Dichroism; D006046:Gold / Q000737:chemistry*; D006493:Heparin / Q000737:chemistry*; D007934:Leuconostoc / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D044366:Transition Temperature
chemical_list: D010455:Peptides; D006046:Gold; D006493:Heparin