13Cα CEST experiment on uniformly 13C-labeled proteins

Area of Science:

• Biochemistry
• Structural Biology
• Nuclear Magnetic Resonance (NMR) Spectroscopy

Background:

• Characterizing low-abundance protein states (minor states) is challenging due to their low signal intensity.
• Traditional NMR methods often struggle to detect and analyze these transient or minor conformations.

Purpose of the Study:

• To develop a new Heteronuclear Single Quantum Coherence (HSQC)-based (13)Cα Chemical Exchange Saturation Transfer (CEST) pulse scheme.
• To enable sensitive detection and structural characterization of otherwise "invisible" minor protein states.

Main Methods:

• A novel HSQC-based (13)Cα CEST pulse scheme was designed.
• The scheme is applicable to uniformly (13)C- or (13)C, (15)N-labeled protein samples in both water and heavy water.
• The method was demonstrated on an acyl carrier protein domain.

Main Results:

• The new (13)Cα CEST scheme exhibits sensitivity comparable to previous methods for selectively labeled samples, even with uniform labeling.
• Data from the acyl carrier protein domain revealed that its minor state possesses significant helical propensity.
• The experiment successfully characterized the minor state of the acyl carrier protein.

Conclusions:

• The developed (13)Cα CEST pulse scheme is effective for structural characterization of minor protein states.
• This advancement facilitates the study of low-abundance protein conformations, providing insights into their structural and functional properties.
• The new method opens avenues for investigating dynamic and transient protein structures.