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Under this funding period we have begun to explore the chemistry of catalytically active hydrolytic metallopeptide motifs.  We have probed the N₃S₂ ligand environment about Co(III) found in the metalloenzymes nitrile hydratase (NHase) and thiocyanate hydrolase.  These metallopeptides are based on the first 12 amino-acids of the primary sequence of nickel-superoxide dismutase with a H(1)C modification and an N-terminal acylation.  We find that after exposure of the peptide to cobalt-dichloride and air, the mature form of the metallopeptide, [Co(III)NHase-m1], is produced.  This metallopeptide contains the Co(III) ion ligated by two amidate nitrogens, a thiolate sulfur and a cis sulfenate/sulfinate motif.  We extensively characterized [Co(III)NHase-m1] by vibrational, optical and X-ray spectroscopies.  We found that mature [Co(III)NHase-m1] will catalyze the hydrolysis of acrylonitrile into acrylamide (58 turnovers after 18 hours).  In order to fully mature [Co(III)NHase-m1], [Co(II)NHase-m1] must be exposed to air for 3 hours.  Shorter air exposure time will only produce Co(III) and one oxygenated thiolate sulfur (an SO₂ moiety), while longer air oxidation produces the bis-SO₂ moiety.  Both of these are inactive as substrate likely cannot bind to the Co-center.

Currently we are attempting to prepare more active NHase mimics.  Our goal is to produce a polymer bound NHase compound that may facilitate the conversion of nitrile based industrial waste under mild condition (i.e. bio-inspired remediation).