What You Need to Know
At temperatures below -20 °C, ice crystals grow and mechanically disrupt hydrogen bonds and hydrophobic interactions that stabilize protein tertiary structure. Rapid freezing in liquid nitrogen limits crystal size, preserving native conformation, while slow freezing allows larger crystals that promote unfolding and aggregation. Extended storage at -80 °C can still lead to protein aggregation over months due to slow molecular rearrangements and ice recrystallization.
The Science
Primary Reaction
Protein denaturation via ice crystal disruption