Association between N-Terminal Pyrenes Stabilizes the Collagen Triple Helix

Area of Science:

• Biochemistry
• Biophysical Chemistry
• Materials Science

Background:

• Collagen triple helix stability is crucial for its biological functions.
• Developing methods to monitor and enhance collagen stability is of significant interest.
• Fluorescent labeling offers a sensitive approach for studying biomolecular interactions and stability.

Purpose of the Study:

• To synthesize pyrene-labeled collagen model peptides.
• To investigate the effect of pyrene labeling on collagen triple helix stability.
• To explore the use of fluorescence spectroscopy for determining thermal denaturation temperatures (Tm).

Main Methods:

• Synthesis of N-terminally pyrene-labeled collagen model peptides with lysine residues for solubility.
• Thermal denaturation studies using circular dichroism (CD) and fluorescence spectroscopy.
• Computational modeling (B3LYP-GD3 and M06-2X) to predict fluorophore interactions and stability.

Main Results:

• Pyrene-labeled triple helices exhibited broad excimer emission around 480 nm, indicating pyrene unit interaction.
• CD experiments revealed that fluorophores enhance helix stability primarily through entropic effects.
• Unfolding temperatures (Tm) increased by up to 21 °C, with fluorescence Tm values closely matching CD-derived values.
• Computational modeling supported face-to-face fluorophore association, consistent with hydrophobic stabilization.

Conclusions:

• N-terminal pyrene labeling is a facile method to promote collagen triple helicity.
• Pyrene fluorescence provides a valuable tool for assessing collagen thermal stability in dilute solutions.
• The study elucidates the role of fluorophore interactions in stabilizing collagen triple helices.