Stop-and-go kinetics in amyloid fibrillation

Area of Science:

• Biophysics
• Biochemistry
• Molecular Biology

Background:

• Protein aggregation and fibrillation are implicated in numerous human diseases.
• Understanding the dynamics of amyloid fibril formation is crucial for disease research.

Purpose of the Study:

• To investigate the real-time dynamics of in vitro glucagon fibrillation.
• To characterize the growth patterns of single amyloid fibrils.

Main Methods:

• Utilized total internal reflection fluorescence microscopy (TIRFM) for high-resolution imaging.
• Performed real-time measurements of single glucagon fibril growth kinetics.

Main Results:

• Amyloid fibril growth occurs intermittently, characterized by periods of growth and extended pauses.
• Exponential distributions of growth and stop times support a Markovian model for fibril state transitions.
• The probability of a fibril being in a growing state is approximately 1/4, and in a stopping state is approximately 3/4, irrespective of individual rate variations.

Conclusions:

• Glucagon fibril formation follows a probabilistic, state-shifting mechanism.
• The findings provide insights into the fundamental processes of amyloidogenesis relevant to disease pathology.