Glucopyranosyl phosphate

Several 1 -phosphates of deoxyfluoro sugars were prepared, and their acid-catalyzed hydrolysis was studied. 2-Deoxy-2-fluoro- (580), 3-deoxy-3-fluoro- (582), 4-deoxy-4-fluoro- (583), and 6-deoxy-6-fluoro-a-D-gluco-pyranosyl phosphates (584) were prepared by treatment of the corresponding per-( -acetylated )9-D-glucopyranoses with phosphoric acid [the p anomer (581) of 580 was prepared by a different method]. The first and second ionization constants (pA a, and pA a2) of these compounds were determined potentiometrically, as well as by the F-n.m.r. chemical shifts at a series of pH values, and then the rate constants of hydrolysis for neutral (B) and monoanion (C) were decided. The first-order rate-constants (k) for 580-584 and a-D-glucopyranosyl phosphate (in Af HCIO4,25 °) were 0.068, 0.175, 0.480, 0.270, 1.12, and 4.10 (all as x lOVs), respectively. The rate... 

The synthesis of linear 4 —> 1-a-D-glucans from D-glucopyranosyl phosphate by the action of phosphorylases has been shown by comparison of results of methylation and end-group assay and viscosity determination,209 and by potentiometric, iodine titrations82 on the product. The chain length of the enzymic product (100 to 200 D-glucose units) is less than that of the natural component. Whether this is due to impure enzymes cannot yet... 

Although no mechanistic studies of this hydrolysis have been reported, the data available suggest that the mechanism is similar to that proposed for the hydrolysis of a-D-glucopyranosyl phosphate in weakly acidic media,332 namely protonation of the glycosyl pyrophosphate derivative and slow heterolysis of the resulting monoanion (79) to produce a cyclic carbonium ion (80), a species considered to be an intermediate in the hydrolysis of glycosides (for a review, see Ref. 333). 

Alkaline hydrolysis of uridine 5 - (a - D- glucopyranosyl pyrophosphate) results in the formation of uridine 5 -phosphate and a-D-glu-copyranose 1,2-cyclic phosphate24 (81). The reaction reaches completion after 30 min at 0° in concentrated aqueous ammonia, or after 2 min at 100° and pH 8.5. Partial conversion of the cyclic phosphate (81) into a-D-glucopyranosyl phosphate and D-glucose 2-phosphate occurs under conditions of elevated temperature. 

Hydrolysis of sugar nucleotides with unspecific pyrophosphatases has already been mentioned (Section 11,1, p. 310). A similar reaction is catalyzed by a bacterial enzyme specific for adenosine 5 -(a-D-glucopyranosyl pyrophosphate).459 The specific conversion of uridine 5 -(a-D-glucopyranosyl pyrophosphate) into a-D-glucopyranosyl phosphate, uridine, and inorganic phosphate was observed with an enzyme from Escherichia colt 459,460 a preparation from Bacillus subtilis can act in a similar manner461 on different sugar nucleotides. ... 

With acetic acid at room temperature, the Brigl anhydride rearranges, to give 1,3,4,6-tetra- 0-acetyl-/3-D-glucopyranose in high yield.213 With dibenzyl hydrogen phosphate, dibenzyl 3,4,6-tri-O-acetyl-/3-D-glucopyranosyl phosphate is formed.2,3a... 

Figure 5. Synthesis of 2-acylamino-2-deoxy-D-glucopyranosyl phosphates using 1-halides as starting materials.

Both anomers of 2-acetamido-2-deoxy-D-glucopyranosyl phosphate have been prepared previously however, the methods used are not easily adapted to obtain glucosamine derivatives carrying 3-hydroxytetradecanoic acid attached to the amino group. 

The starting material was the tri-n-butylammonium salt of 2-deoxy-[(3R)-3-hydroxytetradecanamido]-a-D-glucopyranosyl phosphate which was condensed with... 

Sucrose + inorganic phosphate a-o-glucopyranosyl phosphate + D-fructose... 

The polysaccharide from Hansenula polymorpha 52-251 has a block type of structure of the main chain, with (1— -2)- and (1— 6)-linked a-D-mannopyranosyl units. The side chains also contain (l- 2) links interspersed with (1— 6) links. Immunochemical experiments revealed the presence of a-D-glucopyranosyl phosphate determinants,118 in common with the polysaccharide of Hansenula wingei, a yeast of interest because of its sexual, agglutination factors.104... 

When the enzyme is used for synthesis, no phosphorylated sugar has been found that can replace a-D-glucopyranosyl phosphate, although other D-glucose derivatives, as well as phosphates of D-man-... 

Fig. 3.—Enzymic Interoonversion of D-Glucose and Liver Glycogen. In this reaction, 5-10% of D-glucose is produced, in addition to a-D-glucopyranosyl phosphate.

Percent conversion to a-n-glucopyranosyl phosphate by muscle phosphorylase this is a measure of the exterior chain length. This glycogen was incorrectly described as coming from a case of von Gierke s disease. ... 

A synthesis of glycogen in vitro was reported by Stepanenko and co-workers, who incubated a-n-glucopyranosyl phosphate and a small... 

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