Sugar phosphates starch phosphate

Reeves (1997) has discussed the current recommendations of the American Institute of Nutrition (AIN) for assembling rat diets. Issues discussed include the use of sugar versus starch as the source of carbohydrate, methionine versus cystine as the source of cysteine, and the best oil for providing the essential fatty acids. In embarking on any study, the researcher needs to reevaluate the role of each of the recommended nutrients to make sure that their quantities suit the purposes of the planned experiment. For example, although the AIN recommends using casein as the source of protein, researchers interested in the interactions of calcium and phosphate need to take into accoimt the fact that casein contains significant amounts of phosphate. 

Sugar phosphate found widely in plants, where it is the precursor of starch. 

In the dark, it is assumed that stored starch or other glucan is hydrolyzed to sugar-phosphates which are metabolized to PEP via glycolysis and perhaps to some extent by pentose metabolism. Carboxylation of PEP results largely from atmospheric CO2 to give oxalacetate, which is immediately reduced to malate. Some oxalacetate will ultimately go into aspartate synthesis. Some of the malate will be decarboxylated to pyruvate (or perhaps PEP), where the 3-carbon frag-... 

The function of the sulfate residue in these polysaccharides is unknown but the suggestion has been made that just as starch is synthesised from D-glucose 1-phosphate by the action of phosphorylase, so the seaweed polysaccharides are formed from the appropriate sugar sulfate by reaction with a sulfatase. ... 

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