Urine protein quantification in stacking gel by SDS-PAGE

Area of Science:

• Clinical Chemistry
• Biochemistry
• Analytical Chemistry

Background:

• Urine total protein concentration is crucial for diagnosing kidney disease.
• The pyrogallol red-molybdate (PRM) assay is standard but susceptible to sample interference.
• Accurate protein quantitation is vital for reliable clinical diagnostics.

Purpose of the Study:

• To develop and validate a novel stacking gel-based method for precise urine protein quantitation.
• To address the limitations of interference in conventional assays like PRM.
• To provide a dependable alternative for analyzing clinical urine samples.

Main Methods:

• Utilized SDS-PAGE to concentrate urine proteins into a single band within a stacking gel.
• Employed rapid staining with 0.001% Coomassie at high temperature for visualization.
• Validated the method using Bovine Serum Albumin (BSA) and urine protein standards.

Main Results:

• Demonstrated high correlations for BSA and urine protein standards (R² = 0.997 and 0.990).
• Observed expected increases in protein levels when standards were added to clinical samples with questionable PRM results.
• Showed general consistency with the PRM method (R² = 0.825) but with reduced variation at lower protein concentrations.

Conclusions:

• The stacking gel method provides accurate and reliable urine protein quantitation.
• This technique is a viable alternative for clinical samples where PRM assays yield suspicious results.
• The method effectively minimizes interference issues, enhancing diagnostic accuracy.