Positively charged peptides can interact with each other, as revealed by solid phase binding assays

Joseph Rosenbluh, Anat Kapelnikov, Deborah E. Shalev, Marco Rusnati, Antonella Bugatti, Abraham Loyter*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Solid phase assay systems such as enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR), and overlay gels are used to study processes of protein-protein interactions. The common principle of all these methods is that they monitor the binding between soluble and surface-immobilized molecules. Following the use of bovine serum albumin (BSA)-peptide conjugates or isolated synthetic peptides and the above-mentioned solid phase assay systems, the results of the current work demonstrate that positively charged peptides can interact with each other. Both the ELISA and SPR methods demonstrated that the binding process reached saturation with Kd values ranging between 1 and 14 nM. No interaction was observed between BSA conjugates bearing positively charged peptides and conjugates bearing negatively charged peptides or with pure BSA molecules, strengthening the view that interaction occurs only between positively charged peptides. However, interactions between peptides in solution were not observed by nuclear magnetic resonance (NMR) or by native gel electrophoresis. It appears that for positively charged molecules to interact, one of the binding partners must be immobilized to a surface, a process that may lead to the exposure of otherwise masked groups or atoms. We discuss the relevance of our findings for the use of solid phase assay systems to study interactions between biomolecules.

Original languageAmerican English
Pages (from-to)157-168
Number of pages12
JournalAnalytical Biochemistry
Issue number2
StatePublished - 15 May 2006

Bibliographical note

Funding Information:
This work was supported by a grant from the U.S.–Israel Binational Science Foundation and Israeli Science Foundation (Grant 998/04, A. Loyter). This work was also partially supported by grants from the ISS (AIDS Project) and the AIRC (M. Rusnati).


  • NMR
  • Positively charged peptides
  • Protein-protein interactions
  • SPR


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