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Cobalt‐substituted Fe‐type nitrile hydratase of Rhodococcus sp. N‐771
Author(s) -
Nojiri Masaki,
Nakayama Hiroshi,
Odaka Masafumi,
Yohda Masafumi,
Takio Koji,
Endo Isao
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)01746-9
Subject(s) - nitrile hydratase , chemistry , oxidizing agent , aconitase , enzyme , escherichia coli , nitrile , rhodococcus , medicinal chemistry , cysteine , biochemistry , activator (genetics) , organic chemistry , gene
When the genes encoding α and β subunits of Fe‐type nitrile hydratase (NHase) from Rhodococcus sp. N‐771 were expressed in Escherichia coli in Co‐supplemented medium without co‐expression of the NHase activator, the NHase specifically incorporated not Fe but Co ion into the catalytic center. The produced Co‐substituted enzyme exhibited rather weak NHase activity, initially. However, the activity gradually increased by the incubation with an oxidizing agent, potassium hexacyanoferrate. The oxidizing agent is likely to activate the Co‐substituent by oxidizing the Co atom to a low‐spin Co 3+ state and/or modification of αCys‐112 to a cysteine‐sulfinic acid. It is suggested that the NHase activator not only supports the insertion of an Fe ion into the NHase protein but also activates the enzyme via the oxidation of its iron center.