A simple complex on the verge of breakdown: isolation of the elusive cyanoformate ion.
Why does cyanide not react destructively with the proximal iron center at the active site of 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase, an enzyme central to the biosynthesis of ethylene in plants? It has long been postulated that the cyanoformate anion, [NCCO2](-), forms and then decomposes to carbon dioxide and cyanide during this process. We have now isolated and crystallographically characterized this elusive anion as its tetraphenylphosphonium salt. Theoretical calculations show that cyanoformate has a very weak C-C bond and that it is thermodynamically stable only in low dielectric media. Solution stability studies have substantiated the latter result. We propose that cyanoformate shuttles the potentially toxic cyanide away from the low dielectric active site of ACC oxidase before breaking down in the higher dielectric medium of the cell.
The Atlantic Centre for Green Chemistry, Department of Chemistry, Saint Mary's University, Halifax, Nova Scotia, B3H 3C3, Canada.
Luke J
LJ
Murphy
Katherine N
KN
Robertson
Scott G
SG
Harroun
Christa L
CL
Brosseau
Ulrike
U
Werner-Zwanziger
Jani
J
Moilanen
Heikki M
HM
Tuononen
Jason A C
JA
Clyburne
D000594:Amino Acid Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D002245:Carbon Dioxide / Q000737:chemistry; D020134:Catalytic Domain; D003460:Crystallization; D003486:Cyanides / Q000737:chemistry; D005030:Ethylenes / Q000378:metabolism; D005561:Formates / Q000737:chemistry / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry / Q000302:isolation & purification*; D013816:Thermodynamics; D014961:X-Ray Diffraction
D003486:Cyanides; D005030:Ethylenes; D005561:Formates; D009570:Nitriles; D002245:Carbon Dioxide; C036216:ethylene; D000594:Amino Acid Oxidoreductases; C059460:1-aminocyclopropane-1-carboxylic acid oxidase