Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.2.1.22 (cystathionine beta-synthase)
 965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Crude extracts of wild-type Euglena grown in the light (WTL) or in the dark (WTD) and a mutant lacking detectable plastid DNA (W(3)BUL) contain adenosine 5'-phosphosulfate (APS) sulfotransferase. Isotope dilution experiments indicate that adenosine 3'-phosphate 5'-phosphosulfate (PAPS) sulfotransferase is absent.Thiosulfonate reductase, requiring addition of NADH or NADPH but not ferredoxin, and O-acetyl-l-serine sulfhydrylase, the two other enzymes of the bound intermediate pathway of assimilatory sulfate reduction, are also present. Increasing levels of all three enzymes were found in WTL, WTD, and W(3)BUL during logarithmic growth but the various activities were similar at comparable stages of growth in all three types of cell.These results show that the three enzymes are not coded in the chloroplast DNA and are not restricted to Euglena cells having fully developed chloroplasts. Consistent with this, they do not increase during light-induced chloroplast development in resting cells and are found to be enriched in the mitochondrial fraction. Further resolution of this fraction on sucrose gradients shows that the APS sulfotransferase is associated with both the microbody (glyoxysomal) and mitochondrial fractions while the thiosulfonate reductase and O-acetyl-l-serine sulfhydrylase are associated only with the mitochondria. Thus the three known enzymes of the bound pathway of assimilatory sulfate reduction are present in Euglena mitochondria.Although the activity of the entire bound pathway (APS to cysteine) is low in extracts, addition of dithiothreitol which releases free sulfite from the product of the APS sulfotransferase reaction, causes an increase in reduction activity indicating that a sulfite reductase is also present. It remains to be shown which reducing system is the significant one in vivo in Euglena.
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PMID:Studies of sulfate utilization of algae: 15. Enzymes of assimilatory sulfate reduction in euglena and their cellular localization. 1665 97

To understand the growth response to drought, we performed a proteomics study in the leaf growth zone of maize (Zea mays L.) seedlings and functionally characterized the role of starch biosynthesis in the regulation of growth, photosynthesis and antioxidant capacity, using the shrunken-2 mutant (sh2), defective in ADP-glucose pyrophosphorylase. Drought altered the abundance of 284 proteins overrepresented for photosynthesis, amino acid, sugar and starch metabolism, and redox-regulation. Changes in protein levels correlated with enzyme activities (increased ATP synthase, cysteine synthase, starch synthase, RuBisCo, peroxiredoxin, glutaredoxin, thioredoxin and decreased triosephosphate isomerase, ferredoxin, cellulose synthase activities, respectively) and metabolite concentrations (increased ATP, cysteine, glycine, serine, starch, proline and decreased cellulose levels). The sh2 mutant showed a reduced increase of starch levels under drought conditions, leading to soluble sugar starvation at the end of the night and correlating with an inhibition of leaf growth rates. Increased RuBisCo activity and pigment concentrations observed in WT, in response to drought, were lacking in the mutant, which suffered more oxidative damage and recovered more slowly after re-watering. These results demonstrate that starch biosynthesis contributes to maintaining leaf growth under drought stress and facilitates enhanced carbon acquisition upon recovery.
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PMID:Starch biosynthesis contributes to the maintenance of photosynthesis and leaf growth under drought stress in maize. 3248 92