PLANT PHYSIOLOGY , Vol 106, Issue 2 697-702, Copyright © 1994 by American Society of Plant Biologists
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METABOLISM AND ENZYMOLOGY |
Purification and Characterization of Two Ferredoxin-NADP+ Oxidoreductase Isoforms from the First Foliage Leaves of Mung Bean (Vigna radiata) Seedlings
T. Jin, S. Morigasaki and K. Wada
Department of Biology, Faculty of Science, Kanazawa University, Kakuma, Kanazawa 920-11 Japan
Two forms of Fd-NADP+ oxidoreductase (FNR) isoproteins have been purified
and characterized from the first foliage leaves of 5-d-old mung bean (Vigna
radiata). They could be separated by either Mono Q HR 5/5 or ferredoxin
(Fd)-Sepharose 4B affinity columns. Based on immunoblot analysis and
N-terminal amino acid sequences, one form resembles the FNR purified from
photosynthetic tissues of higher plants and the other resembles that from
nonphotosynthetic tissues. Like their leaf and root FNR counterparts from
spinach and radish, the mung bean leaf FNR isozymes differ from each other
in primary structure and immunogenic properties but are similar in reaction
activities, including cytochrome c reduction and NADP+ photoreduction
assays. The mung bean isozymes also show similar kinetics parameters such
as optimal pH and Km values for Fd and NADPH. Although the function of the
root-type FNR in chloroplasts is not clear from in vitro experiments, we
consider it plausible that it functions nonphotosynthetically, especially
in seedlings at an early development stage. Two Fd isoforms were purified
from young mung bean leaves, as reported on Fds in higher plant leaves.
Based on their N-terminal sequences, both mung bean isoforms were similar
to leguminous leaf Fds.
