Novel, starch-like polysaccharides are synthesized by an unbound form of granule-bound starch synthase in glycogen-accumulating mutants of Chlamydomonas reinhardtii.
stock made from fish and seaweed. Used in Japanese cuisine.
colors that have been certified safe for use in drugs and cosmetics, but not in food by the FDA (the Food and Drug Administration of the U.S.). See .
prepared by heating dry or starch treated with acids. Can be produced from the starch of corn, potatoes or rice
(Dibasic calcium phosphate, Dicalcium orthophosphate) the Dibasic form of .
an emulsifier, humectant and fungicide which is obtained by the action of certain bacteria on
. flavor enhancer derived from meat, fish (sardines), vegetable or fungal source the undercoating of waterfowl (especially ducks and geese). See .
from the digestive tracts of cows and pigs. Can be found in vitamin tablets.
Starch Synthesis in Arabidopsis
In conclusion, based on their expression patterns during seed maturation, four amaranth genes involved in starch synthesis, , , and , can be classed into two groups: (i) is late expresser, which is rapidly expressed at the middle or mid-late stages of seed development; and (ii) , and are steady expressers, which are expressed constitutively throughout seed maturation.
Patent US5824790 - Modification of starch synthesis in plants
Starch is a major storage compound in plants that is present both in leaves and in storage tissues. Biochemical and molecular biological data show that ADP-glucose is the glucosyl donor for plant starch synthesis, and its synthesis is catalyzed by ADP-glucose pyrophosphorylase. Subsequently, starch synthases catalyze the transfer of the glucosyl residue from ADP-glucose to the oligosaccharide chains of the starch components amylose and amylopectin to form new α-1,4-glucosidic residues. After elongation of these α-1,4-glucosidic chains, the branching enzyme catalyzes a cleavage of the elongated chain and transfers the cleaved portion of the oligosaccharide chain to either another region in the amylopectin molecule or to a new amylopectin and forms a new α-1,6-glucosidic linkage. Amylose synthesis is catalyzed by the granule-bound starch synthase. Regulation of starch synthesis occurs at the ADP-glucose pyrophosphorylase step. The enzyme from higher plants, green algae, and cyanobacteria is activated allosterically by 3-phosphoglycerate and inhibited by inorganic phosphate. Isolation of mutants and control analyses indicate that the allosteric activation and inhibition are of physiological and functional importance in the regulation of starch synthesis. Furthermore, evidence indicates that ADP-glucose pyrophosphorylases can also be regulated by a redox mechanism. The current knowledge of the enzyme structures and critical amino acids necessary for substrate binding, allosteric effector binding, regulation, and catalysis for the ADP-glucose pyrophosphorylase is reviewed.
Discovering that Starch is Important to Plants
AB - Sorbitol is a primary end-product of photosynthesis in apple (Malus domestica Borkh.) and many other tree fruit species of the Rosaceae family. Sorbitol synthesis shares a common hexose phosphate pool with sucrose synthesis in the cytosol. In this study, 'Greensleeves' apple was transformed with a cDNA encoding aldose 6-phosphate reductase (A6PR, EC 18.104.22.168) in the antisense orientation. Antisense expression of A6PR decreased A6PR activity in mature leaves to approximately 15-30% of the untransformed control. The antisense plants had lower concentrations of sorbitol but higher concentrations of sucrose and starch in mature leaves at both dusk and predawn. 14CO 2 pulse-chase labeling at ambient CO2 demonstrated that partitioning of the newly fixed carbon to starch was significantly increased, whereas that to sucrose remained unchanged in the antisense lines with decreased sorbitol synthesis. Total activities of ribulose 1,5-bisphosphate carboxylase/oxygenase (EC 22.214.171.124), sucrose-phosphate synthase (EC 126.96.36.199), and ADP-glucose pyrophosphorylase (EC 188.8.131.52) were not significantly altered in the antisense lines, whereas both stromal and cytosolic fructose-1,6- bisphosphatase (EC 184.108.40.206) activities were higher in the antisense lines with 15% of the control A6PR activity. Concentrations of glucose 6-phosphate and fructose 6-phosphate (F6P) were higher in the antisense plants than in the control, but the 3-phosphoglycerate concentration was lower in the antisense plants with 15% of the control A6PR activity. Fructose 2, 6-bisphosphate concentration increased in the antisense plants, but not to the extent expected from the increase in F6P, comparing sucrose-synthesizing species. There was no significant difference in CO2 assimilation in response to photon flux density or intercellular CO2 concentration. We concluded that cytosolic FBPase activity in vivo was down-regulated and starch synthesis was up-regulated in response to decreased sorbitol synthesis. As a result, CO 2 assimilation in source leaves was sustained at both ambient CO 2 and saturating CO2.