Optimization of peptide density on microarray surface for quantitative phosphoproteomics.

Procedures to determine the density of peptides immobilized on a glass surface for the quantitative detection of phosphorylated peptides for phosphoproteomic applications of peptide microarrays are described. Two kinds of representative fluorescent probe molecules, anti-phosphotyrosine antibody (AB) and phos-tag (PT), were examined to compare their ability for the quantitative detection of phosphorylated peptides. PT is a metal complex with a binding specificity to phosphorylated amino acids, and is much smaller in size than AB. Thus, PT is quantitatively bound to the phosphorylated peptides, even at a high immobilization density without steric hindrance, making them highly suited for future microarrays requiring smaller sized peptide spots for much higher throughput.