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In vitro Synthesis of Native, Fibrous Long Spacing and Segmental Long Spacing Collagen
Published on: September 20, 2012
The aggregation behavior of native collagen in dilute solution studied by intrinsic fluorescence and external probing
Kun Wu1, Wentao Liu, Guoying Li
1National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065, China.
Insights
Collagen aggregation in acid solutions was studied. Higher concentrations promote aggregate formation and hydrophobic domains, with specific fluorescence changes indicating ordered structures.
Area of Science:
- Biochemistry
- Biophysics
- Materials Science
Background:
- Type I collagen is a crucial structural protein.
- Understanding collagen aggregation is vital for biomaterials and disease research.
- Collagen's self-assembly properties are concentration-dependent.
Purpose of the Study:
- To investigate the aggregation behavior of type I collagen in acidic solutions.
- To characterize the structural changes and aggregate formation at varying concentrations.
- To identify specific molecular interactions driving collagen aggregation.
Main Methods:
- Fluorescence Resonance Energy Transfer (FRET) between phenylalanine and tyrosine residues.
- 1,8-Anilinonaphthalene sulfonate (ANS) probing for hydrophobic microdomains.
- Guanidine hydrochloride-induced protein unfolding monitored by intrinsic fluorescence.
- Two-dimensional correlation analysis of fluorescence spectra.
Main Results:
- Collagen monomers are within 10nm at 0.30 mg/mL without obvious aggregates.
- Collagen aggregates and hydrophobic microdomains form at 0.45-0.75 mg/mL.
- High-order aggregates indicated by tyrosine fluorescence blue-shift (303 to 293 nm) at 0.90-1.50 mg/mL.
- Proline-aromatic (CH∼π) interactions identified at 298 and 316 nm.
Conclusions:
- Collagen aggregation is concentration-dependent in acidic solutions.
- Specific fluorescence signatures correlate with different aggregation states.
- Hydrophobic interactions and proline-aromatic interactions play key roles in collagen self-assembly.
Abstract:
The aggregation behavior of type I collagen in acid solutions with the concentrations covering a range of 0.06-1.50mg/mL was studied utilizing both of the fluorescence resonance energy transfer (FRET) between the phenylalanine and tyrosine residues and the external probing of 1,8-anilinonaphthalene sulfonate (ANS). FRET at 0.30 mg/mL showed the distance among collagen monomers was within 10nm without the obvious aggregates formed. The predominance of tyrosine fluorescence in FRET in the range of 0.45-0.75 mg/mL identified the existence of collagen aggregates companied with the formation of hydrophobic microdomains revealed by the change of the fluorescence of ANS. The blue-shift of tyrosine fluorescence from 303 to 293 nm for 0.90-1.50mg/mL dedicated the formation of high order aggregates. The results from the two-phase diagrams of the intrinsic fluorescence for the guanidine hydrochloride-induced unfolding of collagen confirmed these conclusions. By the two-dimensional correlation analysis for the intrinsic fluorescence of collagen solutions of 0.45, 0.75 and 1.05 mg/mL, the probable characteristic fluorescence peaks for the interactions of proline-aromatic (CH∼π) among the collagen molecules were found at 298 and 316 nm.
