Reduction equivalents, carbohydrate

Metabolism For uptake and transport of G., see Lit. d-G. plays a central part in the carbohydrate metabolism. It is degraded to smaller molecules in complicated reaction sequences (glycolysis) with release of energy - one example is pyruvic acid, which can enter the citric acid cycle via acetyl-CoA - or (pentose phosphate pathway) can be converted to derivatives of other sugars for biosynthetic purposes under the concomitant availability of reduction equivalents. Alternatively d-G. can be stored in the liver and muscles as areserve substance glycogen (in plants starch). An antimetabolite of d-G. is 5-thio-D-glucose. For detection, see Lit.. ... 

Carbohydrate conversion into new industrial intermediates and end-products like propanediol, methane or syngas needs either net energy input ( reduction equivalents ) or decarboxylation, which results in a significant and costly yield loss and lowers the CO2 fixation net gain. This balance loss is also a conceptual draw-back of present fuel ethanol fermentation from sucrose and starch hydrolysates. So far, the only bulk intermediates with no or minimal... 

The energy equivalent of red light is about 190 kJ (45 kcal) mol-1, but >e actual energy requirement for the reduction of 1 mole ofC02 to carbohydrate is 470 kJ (c==t 112 kcal) mol-1. This shows that the mechanism of... 

Kuen has shown that gases from Fenton reagent-carbohydrate systems consist almost entirely of carbon dioxide. This fact has been exploited for simple, manometric studies of the iron (III) chloride-D-glucono-1,5-lactone-hydrogen peroxide reaction. Equivalent dismutation between carbohydrate fragments, or reduction of carbon dioxide to formic acid, have been suggested in order to account for the deficit (about 66%) in carbon dioxide arising from the oxidative scission. ... 

Similar protocol was applied in the first total synthesis of KDN from non-carbohydrate sources [138]. Catechol derivative 228 was transformed into protected tetraol 235, according to the literature method [139] (Scheme 51). This, in turn, underwent smooth ozonolytic cleavage to give after reductive work-up the ester alcohol, which was converted, over three steps, into the unstable D-mannose derivative 236. Reaction of compound 236 with pyruvate anion equivalent gave a syn product 237, accompanied by the another isomer (3 2). Conversion into KDN was performed in two steps involving ozonolytic cleavage of the double bond, then deprotection with concomitant cyclization using TFA-water mixture. 

Hu and Stampfer [53] also estimated that substimting 1 ounce (-28.35 g) of nuts for the equivalent energy from carbohydrate in an average diet was associated with a 30% reduction in CHD risk. The substitution of nut fat for saturated fet was associated with a 45% reduction in risk. Hu and Stampfer [53] concluded regular nut consumption can be recommended in the context of a healthy and balanced diet. 

Carbohydrates and their derivatives. There are a great many simple carbohydrates available, but one of the most useful is mannose. Reduction to the alcohol gives the C2-symmetric compound mannitol, which can be converted to a useful aldehyde by selective protection as a bis-acetal with acetone and a Lewis acid. Cleavage of the remaining diol with sodium periodate gives two equivalents of a useful protected form of glyceraldehyde. 

Saturated animal fats have been shown to promote an increased level of LDL (Nichols et al., 1957 Walker et al., 1957), and their substitution by equivalent amounts of unsaturated fats promoted a significant decrease of this lipoprotein class. Similar reduction of plasma LDL has been obtained by the isocaloric substitution of saturated fats by carbohydrates (Nichols et al., 1957). Under these conditions, however, high carbohydrate intake may favor increase of the VLDL class (see Section VI, F, 1). 

Carbon flux is the main skeleton of flux distribution. It shutdes from the mitochondria to the cytosol as GAP and is referred here as carbohydrate equivalent (fcHao)- This part of the metabolism is comparable to hetero-trophic growth and the structure of related equations can be translated. For process modeling it is convenient to lump the different steps in the TCA and the PPP and relate aU pooled carbon, energy, and reductant flows to the carbohydrate equivalent. 

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