Structure-Affinity Relationship Analysis and Affinity Maturation of a Calprotectin-Binding Peptide

Area of Science:

• Biochemistry
• Molecular Biology
• Immunology

Background:

• Peptide 3, an 18-amino acid linear peptide, binds the inflammation marker calprotectin with sub-micromolar affinity.
• Existing applications in point-of-care diagnostics show promise, but enhanced affinity is crucial for sensitive and robust assays.

Purpose of the Study:

• To conduct a detailed structure-activity relationship analysis of Peptide 3.
• To improve the binding affinity of Peptide 3 to calprotectin using two distinct strategies.

Main Methods:

• Structure-activity relationship analysis of individual amino acids in Peptide 3.
• Peptide library generation via phage display with random sequence extensions.
• Screening of chemically synthesized peptide variants incorporating non-canonical amino acids.

Main Results:

• Identification of key amino acid residues influencing calprotectin binding.
• Development of Peptide 4 through targeted mutations and non-canonical amino acid incorporation.
• Peptide 4 exhibits a five-fold improved binding affinity (K_D = 39 ± 5 nM) to human calprotectin compared to Peptide 3, as measured by surface plasmon resonance spectroscopy.

Conclusions:

• The study successfully enhanced the binding affinity of Peptide 3 to calprotectin.
• Peptide 4 represents a significant advancement for developing highly sensitive and robust diagnostic assays for inflammation markers.