Cytidine diphosphate-glucose

Cytidine-diphosphate glucose Buffered phosphate diesterase is applied on top of the sample, covered with parafilm and warmed to 23 °C for 45 to 60 mm Cytidine-5 -mono-phosphate and glucose-1-phosphate are formed [42]... 

L-fucose, D-rhamnose GDP-D-mannuronic acid GDP-4-keto-6-deoxy-D-mannose P, P -Diguanosine tetraphosphate P, P -Diguanosine triphosphate Guanosine tetraphosphate Cytidine diphosphate-X CDP-D-glucose CDP-L-ribitol... 

Rubenstein PA, Strpminget jL. Enzymatic synthesis of cytidine diphosphate 3,6-dideoxyheX OSes. Vll. Mechanistic roles of enzyme El and pyridoxamine S -phosphate in the formation of cytidine diphosphace 4-kecO 3,6 dideoxy D-glucose from cytidine diphoisphate-4 keiO 6-deoxy-D-glucose. J Biol Chem 1974 249 3776-3781. 

Whitesides and coworkers have carried out a comparison of enzymic and chemical routes to CTP, GTP and UTP on a 10-gram scale. They concluded that CTP and GTP were best made enzymically, and UTP by reaction of CTP with nitrous acid. The triphosphates were then employed for the enzymic synthesis of UDP-Glucose, UDP-Glucuronic acid, and GDP-Mannose.i94 Cytidine diphosphate sugars have been prepared from the 3,6-dideoxyhexoses paratose and abequose,193 and all four nucleoside diphosphate sugars of 6-sulpho-a-D-quinovose have been synthesized for studies of sulpholipid biosynthesis in chloroplasts.196 The stable analogue (138) of CMP-KDO has been prepared by a triester approach, but was only a weak inhibitor of KDO incorporation into lipopolysaccharides.197 A reference to acetylated forms of UDPGlc is mentioned in Chapter 7. 

In addition to their role as components of nucleoproteins, purines and pyrimidines are vital to the proper functioning of the cell. The bases are constituents of various coenzymes, such as coenzyme A (CoA), adenosine triphosphate (ATP), guanosine triphosphate (GTP), cytidine triphosphate (CTP), diphosphopyridine nucleotide (DPN), triphosphopyridine nucleotide (TPN), and flavin adenine dinucleotide (FAD). A pyrimidine derivative, cytidine diphosphate choline, is involved in phospholipid synthe another pyrimidine compound, uridine diphosphate glucose, is an important substance in carbohydrate metabolism. Cytidine diphosphate ribitol functions in the biosynthesis of a new group of bacterial cell-wall components, the teichoic acids. While mammals excrete nitrogen derived from protein catabolism in the form of urea, birds eliminate their nitrogen by synthesizing it into the purine compound, uric acid. 

The chemical synthesis of several mixed anhydrides such as DPN SS6), XJDP-glucose (336), butyryl adenylate (336a), and amino acid adenylates (336b) have been reported. Cytidine diphosphate choline was formed in good yield by condensing phosphorylcholine with cytidine 5 -... 

When the second substituent in the phosphate is another phosphate instead of an alkyl group, formation of the cyclic compound occurs under mild alkaline treatment. Thus, uridine diphosphate glucose yields uridine monophosphate and glucose cyclic i 2-phosphate and 5-phosphoribosyl P5U ophosphate gives ribose 5-phosphate cyclic i 2-phosphate and inorganic phosphate. Similar changes occur with cytidine diphosphate ribitol and cytidine diphosphate glycerol . 

Inhibition of Cytidine-5 -diphosphate-D-Glucose 4,6-Dehydratase (CDP D-Glucose 4,6-Dehydratase)... 

Figure 11.22 Possible pathways for the synthesis of gangliosides. Cer, ceramide Glc, glucose Gal, galactose GalNAc, N-acetylgalactos-amine CMP, cytidine monophosphate NANA, A/-acetylneuraminic add (sialic acid) UDP, uridine diphosphate. Reproduced from Gurr and James (1980) with permission.

Recently, a universal enzyme-coupled fluorescence assay for glycosyl transferases was developed. This method is extremely cost-effective and is based on the quantification of nucleotides produced in the glycosyl transfer reaction. The guanosine diphosphate (GDP), uridine diphosphate (UDP), and cytidine monophosphate (CMP) are phos-phorylated with nucleotide kinase in the presence of excess of ATP, generating ADP. Via coupled enzyme reactions involving ADP-hexokinase,glucose-6-phosphate dehydrogenase, and diaphorase, the ADP is utilized for the conversion of resazurin to resorufin, which is then quantified by fluorescence measurement. 

The flavoenzyme from Yersinia pseudotuberculosis (YerD) catalyzes in vivo the acyloin condensation of pyruvate to the ketone, cytidine-5 -diphosphate-3,6-di(deoxy)-4-keto-D-glucose [52]. Investigations on its synthetic capabilities revealed that this enzyme can catalyze aldehyde-ketone cross-acyloin condensations, furnishing tertiary alcohols (Table 10.6) [52], Small cyclic aliphatic ketone derivatives, for example, cydohexanone and methylated cyclohexanones, tetrahydro-2H-pyran-3-one (Table 10.6), open-chain ketones containing an ether moiety, diketones, and ketones containing an - or p-ketoesters were aU successfully converted [52],... 

YerE was found to be even more promising. It is an enzyme involved in the biosynthetic pathway of Yersinose A, a branched-chain 3,6-di(deoxy)hexose. It catalyzes the ThDP-dependent coupling of pymvate with cytidine-5 -diphosphate-3,6-di(deoxy)-4-keto-D-glucose. The amino-acid sequence of YerE was found to be very similar to the large subunit of Escherichia coli AHAS (EcAHAS). Furthermore, as for AHAS, YerE was found to suppress the formation of acetolactate in favor of (/ )-PAC. The scope of this new... 

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