Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.1 (nitrate reductase)
 3,728 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A simple and rapid procedure to make yeast cells permeable by agitating with toluene-ethanol, (TE) 1:4, v/v was developed. The permeated cells retained their ability to catalyze certain enzyme reactions. Temperature and duration of agitation during TE treatment played an important role in retention of the catalytic potential of permeated cells. The in situ assay using permeated cell preparations was more sensitive even in the absence of added cofactors than in the vitro assay in detecting assimilatory nitrate reductase (NAD(P)H:nitrate oxidoreductase, EC 1.6.6.2) (NAR) activity in Candida utilis. Using in situ assay technique, different mechanisms regulating the biosynthesis of NAR in C. utilis were investigated. Nitrogen starvation did not lead to derepression of NAR. NO3-ions were absolutely essential for induction and maintenance of high levels of NAR activity. Cells grown on ammonium nitrate possessed relatively lower levels of NAR. Kinetics of NAR induction were followed as a function of time and inducer concentration. The influence of various cations on the induction of NAR by nitrate was investigated. A wide range of D-amino acids induced NAR synthesis. Of 22 L-amino acids tested only phenylalanine induced significant levels of NAR. Various intermediates of the pathway of nitrate reduction influenced the rate of NAR induction. There was a rapid disappearance of in vivo activity of the enzyme of induced yeast cells on nitrogen starvation, and the rate of loss was accelerated by the presence of NH4+.
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PMID:Regulatory properties of yeast nitrate reductase in situ. 94 16

Nuclear transformation of intact (walled) cells of the green alga Chlamydomonas reinhardtii was achieved by agitating the cells in the presence of plasmid DNA and silicon carbide (SiC) whiskers. The protocol was used to introduce the wild-type nitrate reductase structural gene into the nitrate reductase-deficient mutant strain nit1-305. Using SiC whiskers, 10-100 transformants per 10(7) cells were routinely produced, which is comparable to transformation rates achieved by agitating the cells with glass beads. In contrast to the glass bead protocol, cell viability was very high following treatment with SiC, with greater than 80% cell survival after agitation for 10 min. Agitation with SiC whiskers appears to be an efficient method for introducing DNA into intact C. reinhardtii cells and may prove to be applicable to other algal species for which cell wall mutants or protoplasting procedures are unavailable.
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PMID:Transformation of Chlamydomonas reinhardtii with silicon carbide whiskers. 821 58