ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P178. Reactivity for Isocyanide and Nitrile by Using Cobalt(III) Complexes
Directed to an Active Site Model of Nitrile Hydratase
T. Shibayama, T. Yano, Y. Funahashi, T. Ozawa, H. Masuda
Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku,
Nagoya 466-8555, Japan,
e-mail: 19415083@stn.nitech.ac.jp
Nitrile Hydratase (NHase) is an enzyme which hydrates a nitrile compound to the corresponding amide. A noncorrin
Co(III) or a non-heme Fe(III) ion is included in its active site. Crystal structural analyses of their proteins
demonstrated that both metal centers were coordinated by two amide nitrogens from the peptide backbone and
two oxidized cystein sulfurs (Cys-SO and Cys-SO2) in the equatorial plane and a cystein sulfur and H2O (Cotype)
[1] or NO (Fe-type) [2] in the axial positions. (Fig. 1) Recently, Odaka and co-workers reported that Fetype
NHase also hydrolyzed t-butyl isocyanide (tBuNC) to t-butyl amine (tBuNH2) [3].
In order to understand the reaction mechanism, we have prepared and characterized six Co(III) complexes with
N2S2- [4] or N2S3-type ligands [5]; [Co III (L1)(tBuNC)2] - (1) (L1: N, N'-bis((2-mercapto-2-methyl)propioyl)-1, 3propanediamine)
with two thiolate sulfurs, [Co III (L1(SO)2)(tBuNC)2] - (2) with two sulfenate sulfurs and
[Co III (L1(SO2)2)(tBuNC)2]- (3) with two sulfinate sulfurs, [Co III (L2)] - (4) (L2: 3, 3'-bis(2-mercapto-2methylpropionylamino)-dipropylsulfide)
with two thiolate sulfurs, [Co III (L2(SO)(SO2))] - (5) with a sulfenate
sulfur and a sulfinate sulfur, and [Co III (L2(SO2)2)] - (6) with two sufinate sulfurs. In this study, we tried the
hydrolysis reaction of tBuNC and acetonitrile using their complexes under of a large excess of the substrate
concentrate.
References:
[1] A. Miyanaga, S. Fushinobu, K. Ito, T. Wakagi, Biochem. Biophys. Res. Commun., 288, 1169 (2001).
[2] S. Nagashima, M. Nakasako, N. Dohmae, M. Tsujimura, K. Takio, M. Odaka, M. Yohda, N. Kamiya, I.
Endo, Nat. Struct. Biol., 5, 347 (1998).
[3] K. Hashimoto, M. Yohda, M. Odaka, 13th International Conference on Biological Inorganic Chemistry,
Vienna, Austria, Abstr., P133 (July, 2007).
[4] T. Yano, Y. Wasada-Tsutsui, H. Arii, S. Yamaguchi, Y. Funahashi, T. Ozawa, H. Masuda, Inorg. Chem., 46,
10345 (2007).
[5] T. Yano, T. Ikeda, Y. Funanhashi, T. Ozawa, H. Masuda, Adv. Mater. Res., 11-12, 347 (2006).
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