Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.2 (nitrate reductase)
 3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The extraction of glutamine synthetase (GS) from jack pine (Pinus banksiana Lamb.) tissue was facilitated by solubilization of the tissue with 1% or more Nonidet P-40 detergent. In contrast with procedures commonly used to extract GS from other plant tissues, highest recovery of GS was obtained when jack pine tissues were subjected to ultrasonic homogenization in the absence of PVP. Chromatography on DEAE-Sephacel showed that jack pine needles possess two isoforms of GS. Isoform GS(1), which is generally associated with the cytoplasm, eluted at 90 mM KCl and accounted for 80% of total GS activity. Isoform GS(2), which eluted at 280 mM KCl, is generally associated with the chloroplast and is thought to be active in the primary assimilation of ammonium in leaves. Thus GS(2) activity may be important if conifers are to avoid ammonium toxicity under circumstances, such as exposure to nitrous oxides, where nitrate reductase activity is induced in needles. In June, 72% of total GS activity was located in needles. Near the end of the growing season in August, however, only 1% of total GS activity was found in needles whereas 79% was found in roots.
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PMID:The activity, characterization and distribution of the nitrogen assimilation enzyme, glutamine synthetase, in jack pine seedlings. 1497 21

Nitrate reductase utilizing NADH or reduced flavin mononucleotide (FMNH(2)) as electron donor was extracted from the leaves, stems and petioles, and roots of apple seedlings. Successful extraction was made possible by the use of insoluble polyvinylpyrrolidone (Polyclar AT) which forms insoluble complexes with polyphenols and tannins. The level of nitrate reductase per gram fresh weight was highest in the leaf tissue although the nitrate content of the roots was much higher than that of the leaves. Nitrite reductase activity was detected only in leaf extracts and was 4 times higher than nitrate reductase activity. Nitrate was found in all parts of young apple trees and trace amounts were also detected in mature leaves from mature trees. Nitrate reductase was induced in young leaves of apple seedlings and in mature leaves from 3 fruit-bearing varieties. An inhibitor of polyphenoloxidase, 2-mercaptobenzothiazole was used in both the inducing medium and the extracting medium in concentrations from 10(-3) to 10(-5)m with no effect upon nitrate reductase activity.
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PMID:The occurrence of nitrate reductase in apple leaves. 1665 23