Phosphate of sugars

Figure 7.9 Interconversion of sugar phosphates and sugar nucleotide phosphates. Adapted from "Biotechnology of microbial exopolysaccharides". IW Sutherland, Cambridge University Press, 1990.

DNA consists of two strands of sugar-phosphate backbones wound around each other in a double helix. The two helices are connected by hydrogen bonds between the bases. 

Jones, N. R. and Burt, J. R., The separation and determination of sugar phosphates, with particular reference to extracts of fish tissue, Analyst, 85, 810, 1960. 

Of course, it is now established that the glycolysis of glucose to carbon dioxide and ethanol occurs by way of a complex pathway involving 10 different enzymes acting on a variety of sugar phosphate intermediates. The extracellular enzyme preparation that Fischer used was termed invertin, the origin of the term for the enzyme we now know as invertase. He termed the intracellular enzyme yeast-glucase (31) and this enzyme is of the type we now refer to as an amylase. 

In rearrangements (isomerizations, not shown), groups are shifted within one and the same molecule. Examples of this in biochemistry include the isomerization of sugar phosphates (see p.36) and of methylmalonyl-CoA to succinyl CoA (see p. 166). 

In the recombination of sugar phosphates in the regenerative part of the PPP, there are two enzymes that are particularly important ... 

The nonoxidative phase consists of a series of sugar-phosphate interconversions that result in the conversion of ribulose 5-phosphate to ribose 5-phosphate (Figure 6-3). 

Wamelink MM, Struys EA, Huck JH, Roos B, van der Knaap MS, Jakobs C, Verhoeven NM (2005) Quantification of sugar phosphate intermediates of the pentose phosphate pathway by LC-MS/MS application to two new inherited defects of metabolism. J Chromatogr Analyt Technol Biomed Life Sci 823 18-25... 

The individual pathways of carbohydrate metabolism in plants overlap extensively they share pools of common intermediates, including hexose phosphates, pentose phosphates, and triose phosphates. Transporters in the membranes of chloroplasts, mitochondria, amyloplasts, and peroxisomes mediate the movement of sugar phosphates between organelles. The direction of metabolite flow through the pools changes from day to night. 

Chapters 17 through 21 deal with carbohydrate-enzyme systems. Hehre presents some new ideas on the action of amylases. Kabat presents some new immunochemical studies on the carbohydrate moiety of certain water-soluble blood-group substances and their precursor antigens. Hassid reviews the role of sugar phosphates in the biosynthesis of complex saccharides. Pazur and co-workers present information obtained by isotopic techniques on the nature of enzyme-substrate complexes in the hydrolysis of polysaccharides. Gabriel presents a common mechanism for the production of 6-deoxyhexoses. An intermediate nucleoside-5 -(6-deoxyhexose-4-ulose pyrophosphate) is formed in each of the syntheses. 

The Role of Sugar Phosphate in the Biosynthesis of Complex Saccharides... 

Because the transaldolase and transketolase reactions are symmetrical with respect to types of bonds cleaved and formed, their equilibrium constants are near 1. The pool of sugar phosphates is thus near equilibrium in cells that contain these enzymes. In a water-flow analogy, the sugar phosphates and the reactions that interconvert them resemble a large swamp, with ill-defined flows along many interconnecting channels. Water may be fed in from any direction and may leave the swamp in any direction. 

The radical-induced dephosphorylation of sugar phosphates (see Sect. HI,3) and the scission of DNA strands (see Sect. Ill,6) are mainly due to these reactions, at least in the absence of molecular oxygen. 

The pentose phosphate pathway can be divided in two phases an oxidative phase during which glucose-6-phosphate is converted to ribulose-5-phosphate, and a non-oxidative phase constituting of a series of reversible reactions in which two pentose-phosphate residues are converted to a series of sugar-phosphate molecules of differing lengths (Figure 3-2). 

Becker D, Bryant-Friedrich A, Trzasko C-A, Sevilla MD (2003) Electron spin resonance study of DNA irradiated with an argon-ion beam evidence for formation of sugar phosphate backbone radicals. Radiat Res 160 174-185... 

Know the meaning of sugar phosphate, deoxy sugar, amino sugar, ascorbic acid (vitamin C). 

The authors found a 12-fold enhancement of the brown colour (420 nm) of the reaction medium. The reactions, however, were not performed at the same pH. Therefore the quantification by the authors is not very useful, because the formation of brown colour is known to be dependent on the pH the higher the pH, the higher the rate of the colour formation. The same authors reported the use of sugar phosphates, in which the phosphate is covalently bound to the sugar moiety, also leading to a more rapid browning. 

DNA (deoxyribonucleic acid) The basic genetic material found in all living cells (and some viruses), providing the blueprint (i.e. genes) for construction of proteins. DNA is composed of sugars, phosphates, and bases arranged in a double helix, a double stranded, chain-like molecules composed of nucleotide base pairs. 

DNA and RNA are nucleic acids that are composed of sugars, phosphates, and nitrogenous bases (or a base). The four bases found in DNA are guanine (G), cytosine (C), thymidine (T), and adenine (A). Each sugar attached to a base and phosphate is called a nucleotide. Hence, DNA is a collection of nucleotides. 

A solution to the instability of ribose has been offered by Eschenmoser, Arrhenius, and others. It has focused on the generation of sugar phosphates, which have long been known to be more stable to degradation under alkaline conditions. A possible mechanism for forming them is shown in Figure 5.2. 

S. Pitsch, A. Eschenmoser, B. Gedulin, S. Hui and G. Arrhenius (1995). Mineral induced formation of sugar phosphates. Origin Life Evol. Biosph., 25, 297-334. 

Silylation of sugar phosphates requires more drastic conditions [434,435], as follows. 

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