University of Minnesota researchers have used Bio-Rad's Proteominer Technology to profile relative protein abundance and identify post-translationally modified proteins in human saliva.
The researchers found that the Proteominer protein-enrichment kit enhanced identification of changes to low-abundance proteins and detection of post-translationally modified (PTM) proteins.
These findings offer promise for improving differential proteomic analyses and biomarker studies aimed at identifying disease-specific proteins and their PTM variants in various types of biological samples and fluids.
Unlike immunodepletion methods that are sample-specific, the Proteominer kit can be used with a variety of samples.
Proteominer technology consists of millions of unique hexapeptides immobilised on beads; each bead has potentially unique protein-binding properties.
Treatment of samples with the Proteominer kit causes partial depletion of high-abundance proteins and simultaneous concentration of low-abundance proteins, resulting in dynamic range compression (DRC) of samples.
Bandhakavi and his former colleagues at the University of Minnesota compared saliva samples from healthy women with those with metastatic breast cancer and processed the samples with and without using the Proteominer kit.
The researchers' workflow enabled them to identify low-abundance proteins that were affected in breast cancer samples and that retained quantitative accuracy following treatment with the Proteominer kit.
The researchers also demonstrated that DRC could serve as a general methodology for increasing identification of various protein PTMs of biological interest in complex samples.
Knowledge of these PTMs is often critical to understanding a protein's functional state or potential role in disease.
Glycosylated proteins were studied due to their large size and linkage to various diseases.
The researchers coupled the Proteominer technology with covalent glycopeptide enrichment and tandem mass spectrometry.
With DRC, they identified two times more N-linked glycoproteins and their glycosylation sites than without DRC, increasing the known salivary glycoprotein catalogue.
The authors concluded that Proteominer technology should also boost detectability of other biologically interesting PTMs, such as phosphorylation.
