Starch formate

Formic acid gelatinizes starch at room temperature, and at the end of twenty-four hours produces a starch monoformate which is stained 

Starch propionates, with various degrees of propionation up to the tripropionate, have been prepared by refluxing corn starch with propionic acid and propionic anhydride. The lower propionates are water-soluble, but the tripropionate is soluble only in organic solvents. Starch tripropionate and starch tributyrate are easily prepared by treating swollen starch with pyridine and the acid anhydride. These triesters are more soluble in organic solvents than the starch triacetates. 

Both starch tripropionate and tributyrate form clear plastics which, although brittle, are somewhat softer than those of typical whole-starch triacetates. This fact is in keeping with similar results noted for cellulose esters and sustains the view that the mutual attraction of the starch chains is continually rendered less effective as the aliphatic chain increases in length. 

Starch esters of either mono-, di-, or trichloroacetic acid can be pre-pared by heating starch with the appropriate acid or by treatment with the acid anhydride and sulfuric acid. Starch triacetates can be chlorinated by phosphorus pentachloride at 135-140 to produce a starch trichloroacetic ester.  

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Heldt H W, Chon C J, Maronde D, Harold A, Stankovic Z S, Walker D A, Kraminer A, Kirk M R and Heber U (1977), Role of orthophosphate and other factors in the regulation of starch formation in leaves and isolated chloroplasts , Plant Physiol, 59, 1146-1155. 

Leeman, A. M., Karlsson, M. E., Eliasson, A. -C., Bjork, I. M. E. (2006). Resistant starch formation in temperature treated potato starches varying in amylose/amylopectin ratio. Carbohydrate Polymers, 65, 306-313. 

In all types of starch small amounts of phosphorus are present owing to the part played by phosphoric compounds in the enzymatic processes of starch formation. Disregarding a few exceptions,.starch consists of two fundamental components ... 

Another aspect of chloroplast metabolism is synthesis of starch. Formation of ADP-glucose from glucose 1-phosphate is induced by 3-phosphoglycerate, a "feed-ahead" type of regulation (Fig. 23-36). Although fructose 2,6-bisphosphate is absent from chloroplasts, it has an important regulatory function in the cytoplasm of plants as it does in animals.425 430 In the plant cytosol triose phosphates from the chloroplasts are converted to fructose 6-P, glucose 6-P, UDP-... 

Berry, C.S. 1986. Resistant starch Formation and measurement of starch that survives exhaustive digestion with amylolytic enzymes during the determination of dietary fibre. J. Cereal Sci. 4 301-314. 

Formic acid appears to show some selectivity in preferentially esterifying primary hydroxyl groups. Traquair161 describes the preparation of unstable starch formates. The monoformate is believed to be esterified at position 6. The periodate oxidation of monoformates of starch and limit dextrin indicates that ester linkage is predominantly... 

Periodate oxidations usually are carried out in aqueous solution at or below room temperature. Although water is the solvent commonly employed, it is emphasized that periodate oxidation is not limited to water-soluble compounds. Starch, starch formate, and cellulose, sus-... 

Obviously, our understanding of starch biosynthesis is still incomplete, since mutants occur for which the primary metabolic effect has not been determined. Continued evaluation of isozymes and effector compounds, and studies of the in vivo pattern and rate of 14C labeling of intermediates of starch biosynthesis in normal, mutants and mutant combinations should aid in clarifying the nature of the mutations and the pathways of starch biosynthesis. Other aspects of starch formation also remain to be explained. For example, how are starch granules formed as the... 

The C4 cycle can be viewed as an ATP-dependent C02 pump that delivers C02 from the mesophyll cells to the bundle-sheath cells, thereby suppressing photorespiration (Hatch and Osmond, 1976). The development of the C4 syndrome has resulted in considerable modifications of inter- and intracellular transport processes. Perhaps the most striking development with regard to the formation of assimilates is that sucrose and starch formation are not only compartmented within cells, but in C4 plants also may be largely compartmented between mesophyll and bundle-sheath cells. This has been achieved together with a profound alteration of the Benson-Calvin cycle function, in that 3PGA reduction is shared between the bundle-sheath and mesophyll chloroplasts in all the C4 subtypes. Moreover, since C4 plants are polyphyletic in origin, several different metabolic and structural answers have arisen in response to the same problem of how to concentrate C02. C4 plants have three distinct mechanisms based on decarboxylation by NADP+-malic enzyme, by NAD+-malic enzyme, or by phosphoenolpy-ruvate (PEP) carboxykinase in the bundle-sheath (Hatch and Osmond, 1976). 

Liljeberg, H., Akerberg, A., and Bjorck, I. 1996. Resistant starch formation in bread as influenced by choice of ingredients or baking conditions. Food Chem. 56, 389-394. 

Cast (1958), in his investigation of triazine herbicides, found that simazine, like urea herbicides, decreases the accumulation of starch in Coleus blumei. On the other hand, when plants kept in sugar solution were treated with simazine, starch formation was normal, which proved that simazine inhibits sugar synthesis. This result was supported by Moreland et al. (1958), who found that the phytotoxic effect of simazine can be prevented by the addition of carbohydrates. 

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