Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.1.14 (SPS)
 813 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of low phosphate supply (low P) was determined on the diurnal changes in the rate of carbon export, and on the contents of starch, sucrose, glucose, and fructose 2,6-bisphosphate (F2,6BP) in leaves. Low-P effects on the activities of a number of enzymes involved in starch and sucrose metabolism were also measured. Sugar beets (Beta vulgaris L. cv. F58-554H1) were cultured hydroponically in growth chambers and the low-P treatment induced nutritionally. Low-P treatment decreased carbon export from the leaf much more than it decreased photosynthesis. At growth chamber photon flux density, low P decreased carbon export by 34% in light; in darkness, export rates fell but more so in the control so that the average rate in darkness was higher in low-P leaves. Low P increased starch, sucrose, and glucose contents per leaf area, and decreased F2, 6BP. The total extractable activities of enzymes involved in starch and sucrose synthesis were increased markedly by low P, e.g. adenosine 5-diphosphoglucose pyrophosphorylase, cytoplasmic fructose-1,6-bisphosphatase, uridine 5-diphosphoglucose pyrophosphorylase, and sucrose-phosphate synthase. The activities of some enzymes involved in starch and sucrose breakdown were also increased by low P. We propose that plants adapt to low-P environments by increasing the total activities of several phosphatases and by increasing the concentrations of phosphate-free carbon compounds at the expense of sugar phosphates, thereby conserving Pi. The partitioning of carbon among the various carbon pools in low-P adapted leaves appears to be determined in part by the relative capacities of the enzymes for starch and sucrose metabolism.
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PMID:Leaf Phosphate Status, Photosynthesis, and Carbon Partitioning in Sugar Beet: III. Diurnal Changes in Carbon Partitioning and Carbon Export. 1666 61

The green-fruited Lycopersicon hirsutum Humb. and Bonpl. accumulated sucrose to concentrations of about 118 micromoles per gram fresh weight during the final stages of development. In comparison, Lycopersicon esculentum Mill. cultivars contained less than 15 micromoles per gram fresh weight of sucrose at the ripe stage. Glucose and fructose levels remained relatively constant throughout development in L. hirsutum at 22 to 50 micromoles per gram fresh weight each. Starch content was low even at early stages of development, and declined further with development. Soluble acid invertase (EC 3.2. 1.26) activity declined concomitant with the rise in sucrose content. Acid invertase activity, which was solubilized in 1 molar NaCl (presumably cell-wall bound), remained constant throughout development (about 3 micromoles of reducing sugars (per gram fresh weight) per hour. Sucrose phosphate synthase (EC 2.4.1.14) activity was present at about 5 micromoles of sucrose (per gram fresh weight) per hour even at early stages of development, and increased sharply to about 40 micromoles of sucrose (per gram fresh weight) per hour at the final stages of development studied, parallel to the rise in sucrose content. In comparison, sucrose phosphate synthase activity in L. esculentum remained low throughout development. The possible roles of the sucrose metabolizing enzymes in determining sucrose accumulation are discussed.
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PMID:Sucrose Phosphate Synthase, Sucrose Synthase, and Invertase Activities in Developing Fruit of Lycopersicon esculentum Mill. and the Sucrose Accumulating Lycopersicon hirsutum Humb. and Bonpl. 1666 28

Sugar and soluble solids content and invertase (EC 3.2.1.26), sucrose synthase (EC 2.4.1.13), and sucrose phosphate synthase (EC 2.4.1.14) enzyme activities were measured throughout fruit development in tomato (Lycopersicon esculentum Mill.) and the green fruited species Lycopersicon peruvianum. Fruit of L. peruvianum accumulated predominantly sucrose, in contrast with hexose accumulation, which is characteristic of L. esculentum. The percentage of soluble solids in ripe L. peruvianum fruit was more than twice that present in L. esculentum and attributed primarily to the high level of sucrose accumulated in L. peruvianum. Low levels of invertase and sucrose synthase activity were associated with the period of significant sucrose accumulation and storage in L. peruvianum. Increased sucrose phosphate synthase activity was observed during the latter stages of fruit development in sucrose-accumulating fruit but was not coincident with maximum rates of sucrose accumulation.
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PMID:Enzymic Components of Sucrose Accumulation in the Wild Tomato Species Lycopersicon peruvianum. 1666 69

The purpose of this study was to identify the factors that control sucrose-phosphate synthase (SPS)-kinase and SPS-protein phosphatase (SPS-PP) activity in situ, and thereby mediate the activation of SPS by light or mannose. Feeding mannose to excised spinach (Spinacia oleracea) leaves in darkness resulted in a general sequestration of cellular phosphate (as evidenced by accumulation of mannose-6-P and depletion of glucose-6-P [Glc-6-P] and fructose-6-P [Fru-6-P]) and a relatively slow activation of SPS (maximum activation achieved within 90 min). Supplying exogenous inorganic phosphate (Pi) with mannose reduced sequestration of cellular Pi (as evidenced by mannose-6-P accumulation without depletion of hexose-P) and substantially reduced mannose activation of SPS. Thus, depletion of cytoplasmic Pi may be required for SPS activation; accumulation of mannose-6-P alone is clearly not sufficient. It was verified that Glc-6-P, but not mannose-6-P, was an inhibitor of partially purified SPS-kinase, and that Pi was an inhibitor of partially purified SPS-PP. Total extractable activity of SPS-kinase did not vary diurnally, whereas a pronounced light activation of SPS-PP activity was observed. Pretreatment of leaves in the dark with cycloheximide blocked the light activation of SPS-PP (assayed in vitro) and dramatically reduced the rate of SPS activation in situ (in saturating light and carbon dioxide). We conclude that rapid activation of SPS by light involves reduction in cytosolic Pi, an inhibitor of SPS-PP, and light activation of SPS-PP, by a novel mechanism that may involve (directly or indirectly) a protein synthesis step. An increase in cytosolic Glc-6-P, an inhibitor of SPS-kinase, would also favor SPS activation. Thus, the signal transduction pathway mediating the light activation of SPS involves elements of "fine" and "coarse" control.
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PMID:Identification of factors regulating the phosphorylation status of sucrose-phosphate synthase in vivo. 1666 55

The dynamics of dry and fresh weight, the glucose, fructose, sucrose, titratable acid contents, and activities of sucrose-metabolizing and hexose-metabolizing enzymes were examined in developing fruits of bayberry (Myrica rubra Sieb. et Zucc. cvs. 'Wuzi' and 'Biqi'). The results showed the dry and fresh weight of bayberry fruit increased with fruit development and maturation (Fig. 1), with the highest increase rate of dry matters and water occurring during later stage of fruit development (about 10 d before maturation). The change in titratable acid followed a course of "low-high-low" in developing bayberry fruits (Fig. 3). The titratable acid content reached its peak at about 18 d before fruit maturation, and then decreased rapidly. The sugar compositions in fruits of bayberry cv. 'Wuzi' were different from those in fruits of bayberry cv. 'Biqi'. The main sugar accumulated in fruits of bayberry cv. 'Wuzi' was sucrose, accounting for 2/3 of total sugars but the sucrose content in fruits of bayberry cv. 'Biqi' was below 50% of total sugars. The fructose content in fruits of bayberry cv. 'Wuzi' was 4% higher, but that in fruits of bayberry cv. 'Biqi' was 12% lower than glucose content (Fig. 2). The activities of sucrose cleavage enzymes (invertase and cleavage activity of SS) in the fruit of bayberry cv. 'Biqi' increased with fruit development and maturation, but those activities in fruit bayberry cv. 'Wuzi' were almost stable during fruit development with lower levels of enzyme activities in fruit of cv. 'Wuzi' than in cv. 'Biqi' throughout fruit development (Fig. 4 and Fig. 5A). The SPS activity increased during fruit development (Fig. 6), however, the activity peak of synthetic activity of SS occurred at the middle stage of fruit development (Fig. 5B). The FRK activity in fruit of bayberry cv. 'Wuzi' was higher than that of HXK, but the reverse was in fruit of bayberry cv. 'Biqi' (Fig. 7). These results suggested that the 2-3 weeks before fruit maturation was a key phase for the bayberry development and the formation of fruit quality. There was a correlation between water transport and dry matter accumulation. The different sucrose constitutions between two varieties may be attributed to the differences in the activity levels of the sucrose cleavage enzymes while the difference in the ratio of glucose content to fructose content may be caused by the different activity levels of the hexose-metabolizing enzymes.
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PMID:[Carbohydrate metabolism during fruit development of bayberry (Myrica rubra Sieb. et Zucc.)]. 1695 95

Eight chickpea advanced breeding lines (ABLs) and their parents were evaluated for osmotic adjustment (OA), leaf carbohydrates and gas exchange under dryland field . These (ABLs) were derived from crosses between CTS 60543 x Kaniva and Tyson x Kaniva. Mean leaf water potential (LWP) fell down from -1.00 MPa at pre-stress level to about -2.25 MPa during terminal stress. Relative water content (RWC) showed periodic changes with alternate decrease or increase at certain interval, which also influenced the values of OA (low or high) in number of genotypes e.g. Kaniva, CTS 60543, Tyson and M 75. Significant variation in OA ranging 0.45 to 0.88 MPa was observed at high level of stress at -2.5 MPa. However, none of the genotypes showed stability of OA over the period of stress. Leaf starch declined even at mild stress (LWP, -1.6 MPa) resulting in an increase in hexose sugars and activation state of sucrose-phosphate synthase (SPS) that led to accumulation of sucrose. Both photosynthesis (Pmax) and transpiration decreased concurrently in two chickpea lines M 129 and Tyson with increasing water stress. However, rate of decline in the photosynthesis slowed down even drought was further intensified. The observed periodic changes in OA, RWC and photosynthesis appeared to be associated with drought-induced changes in SPS and carbohydrates which modify water uptake of the leaves.
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PMID:Osmotic adjustment increases water uptake, remobilization of assimilates and maintains photosynthesis in chickpea under drought. 1737 71

We studied the storage of sucrose, starch, and hexose before heading in rice (Oryza sativa L.) plants by quantitative trait locus (QTL) analysis with a population of backcross inbred lines (BILs) of japonica cv. Nipponbare x indica cv. Kasalath. Carbohydrates are accumulated in the rice plant before heading and are translated to the panicle after heading. A higher capacity for accumulation is thus a main target for improvement in yield. The form of carbohydrate (sucrose, starch, or hexose) differs depending on the organ in which it is stored. There was no correlation between starch and sucrose or hexose contents in BILs, and the positions of QTLs controlling starch differed from those for sucrose and hexose accumulation. These results suggest that the genetic control of accumulation differs between starch and sugars. QTLs that control the ratio of sucrose to starch content were detected, suggesting the existence of a mechanism(s) that determines this ratio. On chromosome 1, sucrose-phosphate synthase 1, the key enzyme in sucrose synthesis was close to the peaks of the likelihood odds ratios in QTLs for sucrose or hexose content. These results suggest that SPS1 is related to conversion of carbohydrate to sucrose as accumulated form in a plant before heading.
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PMID:Quantitative trait loci for sucrose, starch, and hexose accumulation before heading in rice. 1784 59

Coffee fruits grown in shade are characterized by larger bean size than those grown under full-sun conditions. The present study assessed the effects of shade on bean characteristics and sugar metabolism by analyzing tissue development, sugar contents, activities of sucrose metabolizing enzymes and expression of sucrose synthase-encoding genes in fruits of coffee (Coffea arabica L.) plants submitted to full-sun (FS) and shade (SH) conditions. Evolution of tissue fresh weights measured in fruits collected regularly from flowering to maturation indicated that this increase is due to greater development of the perisperm tissue in the shade. The effects of light regime on sucrose and reducing sugar (glucose and fructose) contents were studied in fresh and dry coffee beans. Shade led to a significant reduction in sucrose content and to an increase in reducing sugars. In pericarp and perisperm tissues, higher activities of sucrose synthase (EC 2.4.1.13) and sucrose-phosphate synthase (SPS: EC 2.4.1.14) were detected at maturation in the shade compared with full sun. These two enzymes also had higher peaks of activities in developing endosperm under shade than in full sun. It was also noted that shade modified the expression of SUS-encoding genes in coffee beans; CaSUS2 gene transcripts levels were higher in SH than in FS. As no sucrose increase accompanied these changes, this suggests that sucrose metabolism was redirected to other metabolic pathways that need to be identified.
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PMID:Effects of shade on the development and sugar metabolism of coffee (Coffea arabica L.) fruits. 1842 Apr 17

A quantitative evaluation of the hydrolysis of wheat starch using Termamyl, a thermostable alpha-amylase (endo-1,4-alpha-d-glucan, glucanohydrolase; EC 3.2.1.78), is reported. Data from the monitoring of the hydrolysis of wheat starch indicated that, after 1 h, glucose and maltooligosaccharides up to DP 7 were the main hydrolysis products and thus enabled optimization of a liquefication step during the production of L-lactic acid. The monitoring system used, both in the on- and off-line mode, was based on continuous flow microdialysis sampling (CFMS) coupled to anion exchange chromatography and integrated pulsed electrochemical detection (IPED). A microdialysis probe equipped with a 5-mm polysulfone (SPS 4005) membrane, with a molecular-weight cut-off of 5 kDa, was used to sample the hydrolysis products of native wheat starch at 90 degrees C. Characteristic fingerprint separations were achieved by anion exchange chromatography after enzymatic hydrolysis. Post-column switching improved the detection and, consequently, also quantification of the hydrolysates as fouling of the electrode could be reduced. Maltooligosaccharide standards were used for quantification and to verify the elution of the hydrolysates by spiking the off-line samples. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 546-554, 1997.
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PMID:Monitoring of enzymatic hydrolysis of starch by microdialysis sampling coupled on-line to anion exchange chromatography and integrated pulsed electrochemical detection using post-column switching. 1864 75

The effect of low temperature on growth, sucrose-starch partitioning and related enzymes in salt-stressed and salt-acclimated cotyledons of quinoa (Chenopodium quinoa Willd.) was studied. The growth of cotyledons and growing axes in seedlings grown at 25/20 degrees C (light/dark) and shifted to 5/5 degrees C was lower than in those only growing at 25/20 degrees C (unstressed). However, there were no significant differences between low-temperature control and salt-treated seedlings. The higher activities of sucrose phosphate synthase (SPS, EC 2.4.1.14) and soluble acid invertase (acid INV, EC 3.2.1.25) were observed in salt-stressed cotyledons; however, the highest acid INV activity was observed in unstressed cotyledons. ADP-glucose pyrophosphorylase (ADP-GPPase, EC 2.7.7.27) was higher in unstressed cotyledons than in stressed ones. However, between 0 and 4days the highest value was observed in salt-stressed cotyledons. The lowest value of ADP-GPPase was observed in salt-acclimated cotyledons. Low temperature also affected sucrose synthase (SuSy, EC 2.4.1.13) activity in salt-treated cotyledons. Sucrose and glucose were higher in salt-stressed cotyledons, but fructose was essentially higher in low-temperature control. Starch was higher in low-temperature control; however, the highest content was observed at 0day in salt-acclimated cotyledons. Results demonstrated that low temperature induces different responses on sucrose-starch partitioning in salt-stressed and salt-acclimated cotyledons. Data also suggest that in salt-treated cotyledons source-sink relations (SSR) are changed in order to supply soluble sugars and proline for the osmotic adjustment. Relationships between starch formation and SuSy activity are also discussed.
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PMID:Low-temperature effect on enzyme activities involved in sucrose-starch partitioning in salt-stressed and salt-acclimated cotyledons of quinoa (Chenopodium quinoa Willd.) seedlings. 1912 55


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