Cytochrome cd1-nitrite
reductase and nitrous oxide reductase of Thiobacillus denitrificans
were purified and characterized by biochemical and immunochemical
methods.
In contrast to the generally soluble nature of the denitrification
enzymes,
these two enzymes were isolated from the membrane fraction of T.
denitrificans
and remained active after solubilization with Triton X-100. The
properties
of the membrane-derived enzymes were similar to those of their soluble
counterparts from the same organism. Nitrous oxide reductase activity
was
inhibited by acetylene. Nitrite reductase and nitrous oxide reductase
cross-reacted
with antisera raised against the soluble enzymes from Pseudomonas
stutzeri.
The nirS, norBC, and nosZ genes encoding the
cytochrome
cd1-nitrite
reductase, nitric oxide reductase, and nitrous oxide reductase,
respectively,
from P. stutzeri hybridized with genomic DNA from T.
denitrificans.
Cross-reactivity and similar N-terminal amino acid and gene sequences
suggest
that the primary structures of the
Thiobacillus enzymes are homologous
to the soluble proteins from
P. stutzeri.