The molten globule state is unusually deformable under mechanical force.

Area of Science:

• Biophysics
• Protein Mechanics
• Cellular Biology

Background:

• The mechanical properties of proteins are crucial for cellular functions.
• Native proteins are generally rigid and brittle.
• The mechanical response of intermediate protein states, like the molten globule, remains less understood.

Purpose of the Study:

• To investigate the mechanical properties of the molten globule state of apomyoglobin.
• To compare the force-induced unfolding of molten globule and native states.
• To understand the implications of molten globule mechanics in cellular processes.

Main Methods:

• Utilized optical trap force spectroscopy to apply and measure forces.
• Studied the response of both native and molten globule states of apomyoglobin.
• Analyzed protein behavior along different pulling axes.

Main Results:

• The molten globule state of apomyoglobin exhibits significant compliance, unlike brittle native proteins.
• This increased compliance makes the molten globule state more deformable.
• The unfolding rate of the molten globule state is highly sensitive to applied force.

Conclusions:

• Molten globule states are generally more compliant and deformable than native proteins.
• The force sensitivity of molten globules suggests a significant role in cellular mechanical processes.
• These findings highlight the importance of protein mechanical properties in cellular function.