Guanosine pyrophosphates

A guanosine tetraphosphate with pyrophosphate groups in the 3 - and 5 -positions was synthesized by double phosphorylation of the corresponding guanosine 3, 5 -dipho-sphate.1501... 

This enzyme [EC 2.7.7.28], also known as NDP-hexose pyrophosphorylase, catalyzes the reaction of a nucleoside triphosphate with a hexose 1-phosphate to produce a NDP-hexose and pyrophosphate (or, diphosphate). In the reverse reaction the NDP-hexose can be, in decreasing order of activity, guanosine, inosine, and adenosine diphosphate hexoses in which the sugar is either glucose or mannose. 

The sugar nucleotides of this group are ubiquitous in Nature. Guanosine 5 -(a-D-glucopyranosyl pyrophosphate) (3) has been found in extracts of mammary gland,68 in various plants,20,69 and in the... 

A trace component present in a preparation of guanosine 5 -(a-D-mannopyranosyl pyrophosphate) from yeast has been identified as a D-glycero-D-manno-he ptosyl ester of guanosine 5 -pyrophosphate.86 This compound seems to be the only known example of a nucleoside diphosphate aldoheptose. ... 

A fructosyl ester of guanosine 5 -pyrophosphate has been reported to occur in Eremothecium ashbyi70 and Candida utilis 87 its structure remains undetermined. 

Uronic acid derivatives are also known among the guanosine 5 -pyrophosphate esters. A mixture of the a-D-mannopyranosyluronic acid ester (20) and, presumably, the /J-L-gulopyranosyluronic acid ester (21) was isolated from the brown alga Fucus gardneri,88 The conversion of the uronic acid in the ester 20 into D-mannitol, and that... 

Among the deoxyhexosyl esters of guanosine 5 -pyrophosphate, the most common is the /3-L-fucopyranosyl ester 22. It was isolated from extracts of Aerobacter aerogenes,90 milk,91 mammary gland,76 and blood cells,48 and was considered of probable occurrence in higher plants also (compare Ref. 92). 

Guanosine 5 -(a-D-rhamnopyranosyl pyrophosphate) (23) was shown to be a product of enzymic reduction of the mannosyl ester (17) in the presence of a plant extract93 or an enzyme preparation from an unidentified strain of Gram-negative bacteria.94,95 In the latter example, the 6-deoxy-D-talosyl ester, presumably 24, is also produced. 

The ester (25) of guanosine 5 -pyrophosphate with 3,6-dideoxy-/3-L-xj/lo-hexopyranose (colitose) was isolated from an extract of... 

Inosine 5 -(a-D-glucopyranosyl pyrophosphate) (50) was obtained by use of the pyrophosphorylases, effective for the respective guanosine derivative, from animal tissues,50 pea,223 or Arthrobacter vis-cosus.218 The enzymic synthesis of the a-D-glucopyranosyl pyrophosphate esters of 2 -deoxyuridine223 and 2 -deoxyadenosine216 has also been described. 

A fermentation procedure has been described237,238 for large-scale production of the latter sugar nucleotide. Bakers yeast transforms guanosine 5 -phosphate into the D-mannosyl pyrophosphate ester in 45% yield when a mixture with D-glucose, potassium phosphate, and magnesium sulfate is incubated. 

Zalitis and Feingold357 were able to observe a trace of activity with the 5 -(a-i> glucopyranosyl pyrophosphates) of cytidine, guanosine, and adenosine in reaction with the liver dehydrogenase. The products have not been identified. 

A purified preparation of the enzyme specific for guanosine 5 -(a-D-mannopyranosyl pyrophosphate) (107c) was obtained from the J-5 mutant strain of Escherichia coli.m The enzyme was found to contain firmly bound NAD . 

Similar 3,6-dideoxyhexosyl-4-ulose derivatives probably intervene in the conversion of guanosine 5 -(6-deoxy-a-D-lyxo-hexopyranosyl-4-ulose pyrophosphate) into the colitose ester, a reaction is catalyzed by an enzyme from Escherichia coli. 7... 

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