2-D hydrophilic interaction liquid chromatography-RP separation in urinary proteomics--minimizing variability through...

Area of Science:

• Biochemistry
• Analytical Chemistry
• Proteomics

Background:

• Urinary proteomics is crucial for biomarker discovery.
• Existing methods often face challenges in protein recovery and workflow compatibility.

Purpose of the Study:

• To optimize a bottom-up urinary proteomics workflow.
• To maximize protein recovery and ensure downstream compatibility.
• To enhance the information yield in urinary proteomic analysis.

Main Methods:

• Optimization of sample enrichment and desalting using centrifugal filtration.
• Adaptation of albumin (HSA) depletion using immunoaffinity chromatography for urine.
• Implementation of off-line 2-D liquid chromatography (HILIC-RP) for peptide separation.
• Minimization of sample handling to reduce process variability.

Main Results:

• Protein recoveries up to 97% achieved with 8 M urea; Tris-HCl/NaCl offered better downstream compatibility (88% recovery).
• Successful adaptation of HSA depletion for urine samples.
• High peak capacity, repeatability, and orthogonality demonstrated by the 2-D chromatographic system.
• Identification of 1668 peptides and 438 proteins from a single urine sample using low-resolution MS/MS.

Conclusions:

• The optimized and streamlined urinary proteomics method demonstrates significant potential for extensive proteomic studies.
• The workflow balances protein recovery, downstream compatibility, and data quality.
• This approach facilitates future advancements in urinary biomarker discovery and diagnostics.