Research into selective biomarkers of erythrocyte exposure to organophosphorus compounds

Genetically Enabling Phosphorus Fluoride Exchange Click Chemistry in Proteins

Phosphorus Fluoride Exchange (PFEx), recently debuted in small molecules, represents the forefront of click chemistry. To explore PFEx's potential in biological settings, we developed amino acids PFY and PFK featuring phosphoramidofluoridates and incorporated them into proteins through genetic code expansion. PFY/PFK selectively reacted with nearby His, Tyr, Lys, or Cys in proteins, both in vitro and in living cells, demonstrating that proximity enabled PFEx reactivity without external reagents. The reaction with His showed unique pH-dependent properties and created thermally sensitive linkages. Additionally, Na2SiO3 enhanced PFEx reactions with Tyr and Cys. PFEx, by generating defined covalent P-N/O linkages, extends the utility of phosphorus linkages in proteins, aligning with nature's use of phosphate connectors in other biomolecules. More versatile and durable than SuFEx, PFEx in proteins expands the latent bioreactive arsenal for covalent protein engineering and will facilitate the broad application of this potent click chemistry in biological and biomedical fields.

Qualitative analysis of the fluorophosphonate-based chemical probes using the serine hydrolases from mouse liver and poly-3-hydroxybutyrate depolymerase (PhaZ) from Bacillus thuringiensis

The serine hydrolase family consists of more than 200 members and is one of the largest enzyme families in the human genome. Although up to 50 % of this family remains unannotated, there are increasing evidences that activities of certain serine hydrolases are associated with diseases like cancer neoplasia, invasiveness, etc. By now, several activity-based chemical probes have been developed and are applied to profile the global activity of serine hydrolases in diverse proteomes. In this study, two fluorophosphonate (FP)-based chemical probes were synthesized. Further examination of their abilities to label and pull down serine hydrolases was conducted. In addition, the poly-3-hydroxybutyrate depolymerase (PhaZ) from Bacillus thuringiensis was demonstrated as an appropriate standard serine hydrolase, which can be applied to measure the labeling ability and pull-down efficiency of FP-based probes. Furthermore, mass spectrometry (MS) was used to identify the serine residue that covalently bonded to the active probes. Finally, these FP-based probes were shown capable of establishing the serine hydrolase profiles in diverse mouse tissues; the serine hydrolases pulled down from mouse liver organ were further identified by MS. In summary, our study provides an adequate method to evaluate the reactivity of FP-based probes targeting serine hydrolases.