Highly Specific Enrichment of Multi-phosphopeptides by the Diphosphorylated Fructose-Modified Dual-Metal-Centered Zirconium-Organic Framework.

Multisite phosphorylation of a protein, generally occurring in biological processes, plays important roles in the regulation of cellular functions. However, the identification of multi-phosphopeptides especially at low abundance is a big challenge as the extreme hydrophilicity and poor ionization efficiency of the multiphosphorylated peptides restrict the deep inspection of multisite phosphorylation processes. In this study, the highly specific enrichment of multiphosphorylated peptides was achieved via the modification of the dual-metal-centered zirconium-organic framework with the diphosphorylated fructose. The diphosphorylated fructose-modified dual-metal-centered zirconium-organic framework (DZMOF-FDP) demonstrated the highly specific affinity to the multiple phosphorylated peptides, with the density functional theory calculations explaining the plausible mechanism for multi-phosphopeptides on the DZMOF-FDP. The selective capture of multi-phosphopeptides from mimic samples confirmed the superior performance of the DZMOF-FDP, with comprehensive comparisons to other modification agents, such as orthophosphate and pyrophosphate. A number of 1871 multiphosphorylated peptides captured by DZMOF-FDP from tryptic digests of HeLa cell lysate could be identified, significantly higher than that by the pristine DZMOF. The deliberately designed modification with diphosphorylated fructose for the dual-zirconium-centered metal-organic framework materials suggests an efficient strategy to develop new enrichment methods in the selective capture of target analytes by judiciously optimizing specific modifiers for adsorbents.