A plasma membrane-bound enzyme of tobacco roots catalyses the formation of nitric oxide from nitrite |
| |
| Authors: | Christine Stöhr Frank Strube Gisela Marx Wolfram R Ullrich Peter Rockel |
| |
| Institution: | Institut für Botanik, Technische Universit?t, Schnittspahnstrasse 10, 64287 Darmstadt, Germany, DE
Institut für Chemie und Dynamik der Geosph?re (ICG-6) Forschungszentrum Jülich GmbH, 52425 Jülich, Germany, DE
|
| |
| Abstract: | Purified plasma membranes (PMs) of tobacco (Nicotiana tabacum L. cv. Samsun) roots exhibited a nitrite-reducing enzyme activity that resulted in nitric oxide (NO) formation. This enzyme
activity was not detected in soluble protein fractions or in PM vesicles of leaves. At the pH optimum of pH 6.0, nitrite was
reduced to NO with reduced cytochrome c as electron donor at a rate comparable to the nitrate-reducing activity of root-specific succinate-dependent PM-bound nitrate
reductase (PM-NR). The hitherto unknown PM-bound nitrite: NO-reductase (NI-NOR) was insensitive to cyanide and anti-NR IgG
and thereby proven to be different from PM-NR. Furthermore, PM-NR and NI-NOR were separated by gel-filtration chromatography
and apparent molecular masses of 310 kDa for NI-NOR and 200 kDa for PM-NR were estimated. The PM-associated NI-NOR may reduce
the apoplastic nitrite produced by PM-NR in vivo and may play a role in nitrate signalling via NO formation.
Received: 8 May 2000 / Accepted: 24 August 2000 |
| |
| Keywords: | :Nicotiana (nitrogen assimilation) Nitrate reductase Nitric oxide Nitrite Plasma membrane Root (nitrogen assimilation) |
| 本文献已被 PubMed SpringerLink 等数据库收录！ |
