Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.26 (invertase)
4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Beta recombinase, a DNA resolvase-invertase, catalyzes in the presence of a chromatin-associated protein such as Hbsu, DNA resolution or DNA inversion on supercoiled substrates containing two directly or inversely oriented target (six) sites. Single crystals of the beta recombinase from plasmid pSM19035 were obtained using the vapor diffusion technique with ammonium phosphate as the precipitating agent. The crystals diffracted X-rays to a maximum resolution of 2.5A. Due to proteolytic degradation during the crystallization experiment, the crystals contain only the N-terminal catalytic domain of beta recombinase corresponding to about 60% of the molecular mass of the initially assayed native protein. The proteolytic removal of the C-terminal DNA-binding domain demonstrated that protein modification can be essential to provide material suitable for X-ray analysis.
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PMID:Proteolytic cleavage of gram-positive beta recombinase is required for crystallization. 1036 Sep 76

Fruits of cv. Fortune mandarin were periodically harvested throughout the ripening period to evaluate changes in carbohydrate content and metabolism in flavedo tissue and to determine the potential role of carbohydrates in the tolerance of citrus fruit to chilling injury (CI). Sucrose showed little change in the flavedo during the season, but fructose and glucose increased, in nearly equal amounts, throughout the fall and winter, reaching a maximum in January. Starch levels were less abundant than soluble carbohydrates and rose continuously until March. Sucrose phosphate synthase (SPS; EC 4.1.14) activity decreased from December throughout ripening. Changes in sucrose synthase (SS; EC 2.4.1.13) and acid and alkaline invertase (Inv; EC 3.2.1.26) activities correlated with changes in the reducing sugars, but acid invertase was less active than the other sucrose-metabolizing enzymes. Carbohydrate changes in the flavedo of Fortune mandarins with fruit maturity appear not to be related to the chilling tolerance of fruits during cold storage.
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PMID:Carbohydrate content and metabolism as related to maturity and chilling sensitivity of cv. Fortune mandarins. 1055 19

The response to moderate salt stress of a Scytonema species isolated from a soil crust in the arid region of central Australia was studied. An increase in intracellular trehalose and sucrose concentrations was detected by NMR and HPLC analysis following salt stress, maximal amounts being produced by exposure to 150 mM NaCl after 48 h. When the organism was subsequently returned to normal growth conditions, the cellular concentrations of these solutes decreased. The biosynthesis of trehalose and sucrose was studied and found, in both cases, to involve both sugar phosphate synthase and phosphatase enzymes. The combined synthase activities and the individual phosphatase activities in cell extracts were increased by salt stress. Trehalose phosphorylase was the only catabolic enzyme detected for trehalose; neither trehalase nor phosphotrehalase activities could be detected. This is the first report of trehalose phosphorylase activity in cyanobacteria. Both trehalose and sucrose phosphorylase activities increased in salt-stressed cells, whereas the activity of invertase did not change.
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PMID:Involvement of the compatible solutes trehalose and sucrose in the response to salt stress of a cyanobacterial Scytonema species isolated from desert soils. 1056 66

We have cloned the gene HXK1 from the dimorphic yeast Yarrowia lipolytica that encodes the unique hexokinase of this yeast. The gene has an intron located 39 base pairs after the A of the first ATG. The putative protein contains a sequence of 40 amino acids which is absent from other known hexokinase sequences. Y. lipolytica strains devoid of hexokinase grew in glucose slower than wild-type. This growth was due to the existence of a glucokinase. The hexokinase from Y. lipolytica substituted effectively for hexokinase II from S. cerevisiae in catabolite repression of invertase. The hexokinases from Schizosaccharomyces pombe or Kluyveromyces lactis were much less effective in this role. The K(m) for glucose and fructose of hexokinase was 0.38 mM and 3.56 mM, respectively. The K(m) of glucokinase for glucose was 0.17 mM. While the hexokinase was strongly inhibited by trehalose-6-phosphate (K(i)=3.6 microM), glucokinase was not affected by this compound.
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PMID:Molecular cloning and characterization of the gene HXK1 encoding the hexokinase from Yarrowia lipolytica. 1057 55

The role of sucrose synthase (SuSy) in tomato fruit was studied in transgenic tomato (Lycopersicon esculentum) plants expressing an antisense fragment of fruit-specific SuSy RNA (TOMSSF) under the control of the cauliflower mosaic virus 35S promoter. Constitutive expression of the antisense RNA markedly inhibited SuSy activity in flowers and fruit pericarp tissues. However, inhibition was only slight in the endosperm and was undetectable in the embryo, shoot, petiole, and leaf tissues. The activity of sucrose phosphate synthase decreased in parallel with that of SuSy, but acid invertase activity did not increase in response to the reduced SuSy activity. The only effect on the carbohydrate content of young fruit was a slight reduction in starch accumulation. The in vitro sucrose import capacity of fruits was not reduced by SuSy inhibition at 23 days after anthesis, and the rate of starch synthesized from the imported sucrose was not lessened even when SuSy activity was decreased by 98%. However, the sucrose unloading capacity of 7-day-old fruit was substantially decreased in lines with low SuSy activity. In addition, the SuSy antisense fruit from the first week of flowering had a slower growth rate. A reduced fruit set, leading to markedly less fruit per plant at maturity, was observed for the plants with the least SuSy activity. These results suggest that SuSy participates in the control of sucrose import capacity of young tomato fruit, which is a determinant for fruit set and development.
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PMID:Antisense inhibition of tomato fruit sucrose synthase decreases fruit setting and the sucrose unloading capacity of young fruit. 1059 Jan 55

The content of free sugars and the activities of enzymes involved in carbon metabolism-sucrose synthase, acid and alkaline invertase, phosphoenol pyruvate carboxylase, malic enzyme and isocitrate dehydrogenase were determined during seed development in mungbean pods. A decrease in carbohydrate content of pod wall from 10 to 25 days after flowering (DAF) and a concomitant increase in the seed till 20 DAF was observed. Sucrose remained the dominant soluble sugar in the pod wall and seed. In the branch of inflorescence and pod wall, the activities of sucrose metabolizing enzymes, viz. acid and alkaline invertase, sucrose synthase (synthesis and cleavage) and sucrose phosphate synthase were higher at 5-10 DAF, whereas in seed the maximum activities of these enzymes were observed at the time of maximum seed filling stage (10-20 DAF). High activities of sucrose synthase at the time of rapid seed filling can be correlated to its sink strength. Higher activities of phosphoenol pyruvate carboxylase in the branch of inflorescence and pod wall than in seed may indicate the involvement of the fruiting structure for recapturing respired CO2. High activities of isocitrate dehydrogenase and malic enzyme in the seed at the time of rapid seed filling could provide NADPH and carbon skeletons required for the synthesis of various seed reserves.
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PMID:Ontogenic changes in enzymes of carbon metabolism in relation to carbohydrate status in developing mungbean reproductive structures. 1072 78

The compartmentation of key processes in sugar, organic acid and amino acid metabolism was studied during the development of the flesh and seeds of grape (Vitis vinifera L.) berries. Antibodies specific for enzymes involved in sugar (cell wall and vacuolar invertases, pyrophosphate: fructose 6-phosphate phosphotransferase, aldolase, NADP-glyceraldehyde-P dehydrogenase, cytosolic fructose 1,6-bisphosphatase), photosynthesis (Rubisco, fructose 1,6-bisphosphatase, sedoheptulose 1,7-bisphosphatase), amino acid metabolism (cytosolic and mitochondrial aspartate aminotransferases, alanine aminotransferase, glutamate dehydrogenase, glutamine synthetase), organic acid metabolism (phosphoenolpyruvate carboxylase, NAD- and NADP-dependent malic enzyme, ascorbate peroxidase), and lipid metabolism (acetyl CoA carboxylase, isocitrate lyase) were used to determine how their abundance changed during development. There were marked changes in the abundance of many of these enzymes in both the flesh and seeds. The intercellular location of some enzymes was investigated using immunohistochemistry. Several enzymes (e.g. phosphoenolpyruvate carboxylase and those involved in amino acid metabolism) were associated with tissues likely to function in the transport of imported assimilates, such as the vasculature. Although other enzymes (e.g. NADP-malic enzyme and soluble acid invertase, involved in the metabolism of sugars and organic acids) were largely present in the parenchyma cells of the flesh, their distribution was extremely heterogeneous. This study shows that when considering the metabolism of complex structures such as fruit, it is essential to consider how metabolism is compartmentalized between and within different tissues, even when they are apparently structurally homogeneous.
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PMID:An immunohistochemical study of the compartmentation of metabolism during the development of grape (Vitis vinifera L.) berries. 1093 59

An expression and secretion system for scytalidopepsin B, an acid protease from Scytalidium lignicolum, was constructed in yeast. Saccharomyces cerevisiae AH22 was transformed with an yeast-E. coli shuttle vector, pAM82, in which an yeast invertase signal segment and the cDNA encoding the pro- and mature enzyme regions were inserted. The transformant was found to secret a pepstatin-insensitive acid protease, when cultured aerobically in a low phosphate (Pi) medium. Amino terminal amino acid sequencing analysis indicated that the recombinant acid protease was accurately processed and secreted as a mature form.
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PMID:Expression and secretion of scytalidopepsin B, an acid protease from Scytalidium lignicolum, in yeast. 1094 80

Detached ears of sorghum (Sorghum vulgare) were cultured in complete liquid medium containing Ca2+(0, 3, 10 and 30 mM) and effect of this ion on the conversion of sucrose to starch with respect to the activities of amylases, sucrose synthase, sucrose phosphate synthase and soluble invertases were studied in developing grains. Presence of 3 mM Ca2+ in culture medium enhanced both accumulation of starch and activity of alpha-amylase in grain but without having any influence on the activity of beta-amylase. However, with 10 and 30 mM Ca2+, the accumulation of starch and activities of both amylases decreased and with advancement in culturing period, starch accumulation was further decreased. Irrespective of its concentration, Ca2+ enhanced the activities of sucrose synthase (synthesis), sucrose-phosphate synthase, soluble acid invertase and soluble-neutral invertase. Increase in the concentration of Ca2+ in culture medium was concomitant with an elevation in relative proportion of sucrose in the grain reflecting a net balance in per cent increase with Ca2+ in the activities of sucrose-synthesizing enzymes over sucrose-hydrolysing ones. Based on the results, it is suggested that assimilation of Ca2+ by grain is essential for maintaining high activity of alpha-amylase to generate starch primers required for the conversion of sucrose to starch during grain filling in sorghum.
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PMID:Calcium-mediated conversion of sucrose to starch in relation to the activities of amylases and sucrose-metabolizing enzymes in sorghum grains raised through liquid culture. 1098 25

Plants lack specialised organs and circulatory systems, and oxygen can fall to low concentrations in metabolically active, dense or bulky tissues. In animals that tolerate hypoxia or anoxia, low oxygen triggers an adaptive inhibition of respiration and metabolic activity. Growing potato tubers were used to investigate whether an analogous response exists in plants. Oxygen concentrations fall below 5% in the centre of growing potato tubers. This is accompanied by a decrease of the adenylate energy status, and alterations of metabolites that are indicative of a decreased rate of glycolysis. The response to low oxygen was investigated in more detail by incubating tissue discs from growing tubers for 2 hours at a range of oxygen concentrations. When oxygen was decreased in the range between 21% and 4% there was a partial inhibition of sucrose breakdown, glycolysis and respiration. The energy status of the adenine, guanine and uridine nucleotides decreased, but pyrophosphate levels remained high. The inhibition of sucrose breakdown and glycolysis was accompanied by a small increase of sucrose, fructose, glycerate-3-phosphate, phosphenolpyruvate, and pyruvate, a decrease of the acetyl-coenzymeA:coenzymeA ratio, and a small increase of isocitrate and 2-oxoglutarate. These results indicate that carbon fluxes are inhibited at several sites, but the primary site of action of low oxygen is probably in mitochondrial electron transport. Decreasing the oxygen concentration from 21% to 4% also resulted in a partial inhibition of sucrose uptake, a strong inhibition of amino acid synthesis, a decrease of the levels of cofactors including the adenine, guanine and uridine nucleotides and coenzymeA, and attenuated the wounding-induced increase of respiration and invertase and phenylalanine lyase activity in tissue discs. Starch synthesis was maintained at high rates in low oxygen. Anoxia led to a diametrically opposed response, in which glycolysis rose 2-fold to support fermentation, starch synthesis was strongly inhibited, and the level of lactate and the lactate:pyruvate ratio and the triose-phosphate:glycerate-3-phosphate ratio increased dramatically. It is concluded that low oxygen triggers (i) a partial inhibition of respiration leading to a decrease of the cellular energy status and (ii) a parallel inhibition of a wide range of energy-consuming metabolic processes. These results have general implications for understanding the regulation of glycolysis, starch synthesis and other biosynthetic pathways in plants, and reveal a potential role for pyrophosphate in conserving energy and decreasing oxygen consumption.
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PMID:Metabolic activity decreases as an adaptive response to low internal oxygen in growing potato tubers. 1103 Apr 30


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