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Evidence for an NO‐rebound, mechanism for production of N 2 O from nitrite by the copper‐containing nitrite reductase from Achromobacter cycloclastes
Author(s) -
Jackson M.A.,
Tiedje J.M.,
Averill B.A.
Publication year - 1991
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 - 10.1016/0014-5793(91)81099-t
Subject(s) - nitrite reductase , nitrite , chemistry , yield (engineering) , enzyme , reductase , copper , nitrate , biochemistry , inorganic chemistry , organic chemistry , materials science , metallurgy
Reduction of NO − 2 by the Cu‐containing nitrite reductase from Achromobacter cycloclastes produces NO as the primary product initially, but as NO accumulates, NO production levels‐off and N 2 O production becomes significant. Reaction of the enzyme with NO − 2 in the presence of NO increases the amount of N 2 O product significantly, while trapping the NO product as nitrosylhemoglobin or rapid, removal of NO by sparging results in no detectable N 2 O production. Reaction of the enzyme with 15 NO − 2 in the presence of 14 NO results in rapid formation of the mixed isotope product ( 14 N, 15 N)O in ca. 45% yield. In contrast, the presence or absence of NO has no effect on N 2 O production by a prototypical heme cd 1 ‐containing nitrite reductase. These results are consistent with formation of a labile Cu + −NO + species in the copper enzyme, which normally decomposes to NO. Production of N 2 O requires that the released NO must rebind to the enzyme to combine with a second NO − 2 or a species derived therefrom.