A luminescent ATCUN peptide variant with enhanced properties for copper(II) sensing in biological media.

Abstract

The measurement of labile CuII in biological samples is fundamental for understanding Cu metabolism and has been emerging as a promising diagnostic marker for Cu-related pathologies such as Wilson's and Alzheimer's diseases. The use of fluorescent chelators may be useful to circumvent separation steps employed by current methods. For this purpose, we recently designed a selective and suited-affinity turn-off luminescent probe based on a peptide bearing the CuII-binding Xxx-Zzz-His (Amino-Terminal CuII- and NiII-binding, ATCUN) motif and a TbIII-DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) complex. Here, we present an analogue probe bearing the ATCUN motif variant Xxx-His-His. This probe showed much faster response in biologically-relevant media and higher stability than the previous motif at low pH. These features could be beneficial to the measurement of dynamic CuII fluctuations and the application in slightly acidic media, such as urine.