Protease-dependent fractional mass and peptide properties

Area of Science:

• Proteomics
• Analytical Chemistry
• Biochemistry

Background:

• Mass spectrometry (MS) for peptide analysis relies on specific protease cleavage.
• Protease specificity leads to non-random amino acid distribution in peptides.
• Physicochemical effects of this distribution are well-studied for trypsin but less so for other proteases.

Purpose of the Study:

• Investigate relationships between peptide fractional mass, isoelectric point (pI), and hydrophobicity.
• Analyze protease-dependent properties of peptides generated from human proteins.
• Explore the utility of fractional mass information in peptide mass fingerprinting.

Main Methods:

• Utilized all human proteins from the Swiss-Prot database.
• Analyzed peptides generated by specific proteases: trypsin, chymotrypsin, and gluC.
• Examined distributions of fractional masses and average regression lines.

Main Results:

• Fractional mass distributions and regression lines showed similarities but also differences among proteases (trypsin, chymotrypsin, gluC).
• GluC exhibited the steepest fractional mass regression line.
• Individual protein regression lines varied up to +/-100 ppm from the average, indicating protease-dependent peptide properties.

Conclusions:

• Peptide fractional mass and other properties are significantly influenced by the protease used for digestion.
• Increasing MS instrument accuracy allows for exploitation of fractional mass data in peptide identification.
• Findings enhance understanding of protease specificity in proteomics and MS-based analyses.