Rapid and Simple Analysis of the Human Pepsin Secondary Structure Using a Portable Raman Spectrometer.

Area of Science:

• Biochemistry
• Spectroscopy
• Protein Science

Background:

• Human pepsin is a key digestive protease whose bioactivity depends on its secondary structure.
• Analyzing human pepsin secondary structure is complex but crucial for understanding its biological function.
• Existing methods for analyzing protein secondary structure can be challenging.

Purpose of the Study:

• To develop a convenient and rapid method for detecting human pepsin secondary structure changes.
• To correlate secondary structure alterations with human pepsin activity and bioactivity.
• To establish a sensitive detection method for human pepsin as a disease marker.

Main Methods:

• Utilized a portable Raman spectrometer to analyze human pepsin.
• Employed surface-enhanced Raman spectroscopy (SERS) to detect changes in pepsin secondary structure at varying pH.
• Validated findings using circular dichroism (CD) measurements.

Main Results:

• Observed a gradual increase in beta-sheet content with increasing pH, consistent with CD data.
• Demonstrated that secondary structure changes enhance the sensitivity of SERS detection for human pepsin.
• Achieved a detection limit of 2 μg/mL for human pepsin, with 80.7-92.3% recovery in simulated saliva samples.

Conclusions:

• The developed SERS method offers a promising approach for studying protein secondary structure.
• This technique has significant potential for advancing clinical diagnosis, particularly for gastroesophageal reflux disease (GERD).
• The method provides a sensitive and efficient tool for analyzing protein structure and function.