Heterogeneous Structure and Dynamics of Water in a Hydrated Collagen Microfibril

Area of Science:

• Biophysics
• Materials Science
• Biochemistry

Background:

• Collagen type I fibrils possess remarkable mechanical properties due to their hierarchical structure.
• Water content significantly influences collagen fibril properties, yet its specific interactions remain understudied.
• Collagen fibrils are complex heterofibrils composed of protein, macromolecules, and water.

Purpose of the Study:

• To model collagen type I fibrils as hydrated microfibril crystals.
• To investigate the structural and dynamic properties of water within collagen fibrils across varying hydration levels.
• To understand the role of water in collagen fibril stability and disassembly.

Main Methods:

• Large-scale all-atom molecular dynamics simulations were employed.
• Simulations covered hydration levels from physiological conditions to fibril disassembly.
• Analysis focused on water properties, hydrogen bonding, and tropocollagen packing.

Main Results:

• Water properties and dynamics vary significantly with hydration level and spatially within the fibril structure.
• Alterations in water properties initiate in the gap regions of the microfibril.
• Water transitions from a 'glue' to a 'lubricant' role around 100% hydration, preceding disassembly beyond 130%.

Conclusions:

• Water plays a critical role in collagen fibril structure and mechanics, with distinct spatial and hydration-dependent properties.
• The hydration-dependent behavior of water influences collagen fibril stability and disassembly.
• Findings offer insights into collagen's mechanical properties and potential implications for mineralization.