Bio-MEMS - Bio-MEMS For Diagnostics - Genomic and Proteomic Microarrays - Peptide and Protein Microarrays

Peptide and Protein Microarrays

The motivation for using peptide and protein microarrays is firstly because mRNA transcripts often correlate poorly with the actual amount of protein synthesized. Secondly, DNA microarrays cannot identify post-translational modification of proteins, which directly influences protein function. Thirdly, some bodily fluids such as urine lack mRNA. A protein microarray consists of a protein library immobilized on a substrate chip, usually glass, silicon, polystyrene, PVDF, or nitrocellulose. In general, there are three types of protein microarrays: functional, analytical or capture, and reverse-phase protein arrays.

• Functional protein arrays display folded and active proteins and are used for screening molecular interactions, studying protein pathways, identifying targets for post-translational modification, and analyzing enzymatic activities.
• Analytical or capture protein arrays display antigens and antibodies to profile protein or antibody expression in serum. These arrays can be used for biomarker discovery, monitoring of protein quantities, monitoring activity states in signalling pathways, and profiling antibody repertories in diseases.
• Reverse-phase protein arrays test replicates of cell lysates and serum samples with different antibodies to study the changes in expression of specific proteins and protein modifications during disease progression, as well as biomarker discovery.

Protein microarrays have stringent production, storage, and experimental conditions due to the low stability and necessity of considering the native folding on the immobilized proteins. Peptides, on the other hand, are more chemically resistant and can retain partial aspects of protein function. As such, peptide microarrays have been used to complement protein microarrays in proteomics research and diagnostics. Protein microarrays usually use Escherichia coli to produce proteins of interest; whereas peptide microarrays use the SPOT technique (stepwise synthesis of peptides on cellulose) or photolithography to make peptides.