Illinois State University, Chemistry, Normal, IL 61790-4160
There are many benefits to examining argentocyanide and aurocyanide, ([M(CN)2], M= Ag(I), Au(I)) reactions with biologically active ligands under biomimetic conditions. These two compounds are known to interact with thiols which can displace the cyanide by a ligand exchange reaction. They are useful tools for research on the Cystic Fibrosis transmembrane conductance regulator (CFTR). Cystic Fibrosis is a disease caused by a defective CFTR protein, which is formed due to the inherited gene associated with this malady. When a CFTR mutant is present, the passage of chloride through cell membranes cannot be regulated by cells in the body. Argentocyanide and aurocyanide are particularly interesting because they have identical linear structures but inhibit the CFTR constructs with an interchannel cysteine differently. The difference may lie in the ability of silver to form three- and four-coordinate complexes. UV-Visible Spectroscopy and Electrospray Ionization  Mass Spectrometry are being used to examine the reactions of cyanide and cysteine with [Ag(CN)2] . Negative ion spectra of authentic KAg(CN)2 exhibited the expected [Ag(CN)2 ] signals at m/z =159 and 161due to 107Ag and 109Ag isotopes. Unexpectedly, multinuclear complex anions with the formula Agn(CN)n+1, n=2,3,4 and a potassium-linked disilver complex, all having the correct isotopic patterns, were observed. The positive ion spectra revealed a series of dipotassiated complexes, [K2Agn(CN)n+1]+, n=1,2,3. When excess cyanide was utilized, evidence for the expected [Ag(CN)3]2 was not observed as (m+1)/1 or m/2 signals. Negative ion spectra with excess K13CN revealed rapid equilibration of free and bound cyanides in [Ag(CN)2 ] and all of the multi-silver complexes. Studies with cysteine have just been initiated and preliminary results will be reported in the poster.
[Abstract (DOC)]