"Naked-eye" detection of histidine by regulation of Cu(II) coordination modes.
The association of various alpha-amino acids with four new, coordinatively unsaturated metal complexes ([Cu(5)]2+, [Cu(6)]2+, [Cu(7)]2+, and [Zn(8)]2+) was examined. The receptors [Cu(5)]2+ and [Cu(7)]2+ were found to discriminate histidine (His) from other zwitterionic alpha-amino acids by means of indicator-displacement assays (IDAs) using 5(6)-carboxyfluorescein as an indicator in buffered methanol/water (3:1) solvent. The colorimetric detection of His was achieved by using this IDA method, which appears to owe its selectivity to a unique process involving disruption of the host complex to form a 2:1 His/Cu(II) complex rather than simple indicator displacement. The occurrence of distinct intermolecular coordination processes in response to the introduction of a different amino acid is observed. X-ray crystal structures of the host metal complexes were obtained and exhibit the adoption of a variety of coordination geometries about the metal center.
Folmer-Andersen
J Frantz
JF
Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78701, USA.
Lynch
Vincent M
VM
Anslyn
Eric V
EV
D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006639:Histidine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008958:Models, Molecular; D013056:Spectrophotometry, Ultraviolet
D006639:Histidine; D003300:Copper