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NADH‐dependent Fe 3+ EDTA and oxygen reduction by plasma membrane vesicles from barley roots
Author(s) -
Brüggemann Wolfgang,
Moog Petra R.
Publication year - 1989
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1989.tb06176.x
Subject(s) - chemistry , hordeum vulgare , isoelectric point , catalase , reductase , biochemistry , antimycin a , oxidoreductase , enzyme , isoelectric focusing , polyacrylamide gel electrophoresis , electron transport chain , biology , ecology , poaceae
Brüggemann, W. and Moog, P. R. 1989. NADH‐dependent Fe 3+ EDTA and oxygen reduction by plasma membrane vesicles from barley roots. Biochemical properties of pyridine‐dinucleotide‐dependent Fe 3+ ‐EDTA reductase were analysed in purified plasma membranes (PM) from barley ( Hordeum vulgare L. cv. Marinka) roots. The enzymatic activity preferred NADH over NADPH as electron donor and it was 3‐fold increased in the presence of detergent. The reductase showed a pH optimum of 6.8 and saturable kinetics for NADH with K m (NADH) of 125 μM and V max of 143 nmol Fe (mg protein) ‐1 min ‐1 in the presence of 500 μ M Fe 3+ EDTA. For the dependence of the reaction rate on the iron compound, K m (Fe 3+ EDTA) of 120 μM and V max of 184 nmol (mg protein) ‐1 min ‐1 were obtained. The activity was insensitive to superoxide dismutase (SOD; EC 1.15.1.1), catalase (EC 1.11.1.6) and antimycin A, but stimulated by an oxygen‐free reaction medium. It could be solubilized by 0.25% (w/v) Triton X‐100. The solubilized enzyme revealed one band in native polyacrylamide gel electrophoresis (PAGE) and in isoelectric focussing (IEF) at pl 7.4 by enzyme staining. Major polypeptides with molecular weights of 94, 106, 120 and 205 kDa corresponded to the enzyme‐stained band from native PAGE. Analysis of oxygen consumption by the membranes revealed the existence of NADH:CK oxidoreductase activity, which was stimulated by salicylhydroxamic acid (SHAM), chinhydron, Fe 3+ EDTA and Fe 3+ EDTA but not by K 3 [Fe(CN) 6 ] or K 4 [Fe (CN) 6 ). The stimulating effect of the iron chelates on oxygen consumption was due to Fe 2+ and could be suppressed by bathophenanthroline disulfonate (BPDS), SOD and p ‐chloromercurophenylsulfonic acid (PCMS). The results are discussed with respect to the nature of the stimulation.