Organotellurium scaffolds for mass cytometry reagent development

Abstract

Mass cytometry (MC) is a powerful tool for studying heterogeneous cell populations. In previous work, our laboratory has developed an MC probe for hypoxia bearing a methyl telluride mass tag. The methyl telluride was unoptimized, displaying stability and toxicity limitations. Here, we investigate three classes of organotelluriums as MC mass tags: methyl tellurides, trifluoromethyl tellurides and 2-alkyl-tellurophenes. NMR was used to compare the stability of these compounds in aqueous and organic solutions and the compounds were analysed for toxicity in Jurkat cells. The methyl tellurides were moderately stable to aerobic oxidation in organic solution under dry ambient conditions. The trifluoromethyl tellurides were stable to aerobic oxidation in organic solution but decomposed in aqueous solution. The 2-alkyl-tellurophenes proved to be stable in both organic and aqueous solutions under ambient conditions and showed limited toxicity (IC50 > 200 μM) in cell based assays. The synthetic feasibility, chemically stability, and limited toxicity of tellurophenes suggests these groups will be good choices for MC reagent development.

TePhe, a tellurium-containing phenylalanine mimic, allows monitoring of protein synthesis in vivo with mass cytometry

“…Similar to other tellurophenes, TePhe is stable under ambient aqueous buffered conditions for weeks (SI Appendix, Fig. S3) (18).…”

“…Telluromethionine (TeMet) has the potential to be used to monitor protein synthesis by MC as it is taken up into synthesized proteins and Te can be readily detected by MC, but TeMet is unstable and toxic, making its use challenging (17). Due to favorable stability and toxicity characteristics of tellurophenes, a Tecontaining analog of 2-thienylalanine was investigated (18). In vivo, 2-thienylalanine is observed to be incorporated into protein as a phenylalanine surrogate (19,20).…”

Validation of l‐Tellurienylalanine as a Phenylalanine Isostere

“…Moreover, the isosteric nature of TePhe could be potentially generalized to tellurophenes as phenyl mimics, thus greatly increasing the potential for novel probe generation. The use of TePhe isotopologues, multiplexed with additional MC reagents, will enable time‐resolved experiments and deep‐profiling of biological samples at a cellular level . Ongoing work is also focused on the production of recombinant proteins through metabolic incorporation of TePhe.…”

Isotopologous Organotellurium Probes Reveal Dynamic Hypoxia In Vivo with Cellular Resolution

“…Our previous MC‐compatible hypoxia probe exhibited favorable activity in vitro, but failed to reliably identify hypoxic cells in vivo likely due to the stability of the telluroether . Chemical optimization of the organotellurium mass tag revealed that a more stable tellurophene would likely yield a better performing probe . Indeed, combining a 2‐nitroimidazole (2‐NI) with a tellurophene produced a probe (Telox 2) with excellent solution stability and low toxicity both in vitro and in vivo (Figure b; Supporting Information, Figures S1, S2, and S6).…”