Tetracyanoresorcin[4]arene selectively recognises trimethyllysine and inhibits its enzyme-catalysed demethylation

Nϵ-methylation of lysine within proteins is a critical biological process that, among other roles, is involved in the control of gene expression. Compounds that recognise Nϵ-methylated lysine may therefore be useful probes for the study of the associated biological mechanisms and have therapeutic potential. Here, we show that tetracyanoresorcin[4]arene (1) selectively recognises Nϵ-trimethyllysine and binds to Nϵ-trimethyllysine within the context of a short peptide. Its binding properties compare favourably to a previously characterised Nϵ-trimethyllysine binder, p-sulfonatocalix[4]arene (2). We also show that both 1 and 2 inhibit the demethylation of Nϵ-trimethyllysine within a histone-derived peptide by the histone demethylase KDM4A.