Native-like secondary structure of molten globules

Area of Science:

• Biochemistry
• Structural Biology
• Spectroscopy

Background:

• Far-UV circular dichroism (CD) is a key technique for analyzing protein secondary structure.
• While native protein CD spectra are well-understood, studies on denatured states are less common.
• Understanding protein structure in non-native states like molten globules is crucial for protein folding research.

Purpose of the Study:

• To investigate and quantify the secondary structure content of proteins in the molten globule state using CD spectroscopy.
• To compare the secondary structure of molten globules with their native counterparts.
• To establish a correlation between CD spectra and secondary structure composition in molten globule proteins.

Main Methods:

• Acquisition and analysis of far-UV CD spectra for nine proteins in native and pH-induced molten globule states.
• Application of singular value decomposition to analyze the spectral components of molten globules.
• Development of a self-consistent procedure to correlate CD spectral shape with secondary structure content.

Main Results:

• Singular value decomposition indicated that molten globule spectra can be represented by at least three independent structural components (alpha-helix, beta-structure, irregular).
• A strong correlation (Pearson coefficient of 0.9) was found between the CD spectra of molten globules and the secondary structure content of native proteins.
• The analysis revealed that secondary structure elements in the molten globule state closely resemble those in the native state.

Conclusions:

• Proteins in the molten globule state largely preserve their native secondary structure.
• Far-UV CD spectroscopy is a reliable method for assessing secondary structure in molten globule proteins.
• The findings contribute to a deeper understanding of protein folding intermediates and conformational stability.