Diphosphatase, nucleoside

NAD GLYCOHYDROLASE Hydrolysis of nucleoside diphosphate, NUCLEOSIDE DIPHOSPHATASE Hydrolysis of 3 -ribonucleotide,... 

NUCLEOSIDE DIPHOSPHATASE NUCLEOSIDE DIPHOSPHATE KINASE HALF-REACTIONS... 

Histochemical studies on Raillietina (.Raillietina) johri (Cestoda Davaineidae). II. Nucleoside diphosphatase and thiamine pyrophosphatase. Journal of Helminthology, 53 261-3. 

Trombetta, E. S., and Helenius, A. (1999). Glycoprotein reglucosylation and nucleotide sugar utilization in the secretory pathway Identification of a nucleoside diphosphatase in the endoplasmic reticulum. EMBO J. 18, 3282-3292. 

In the liver, ThDP can be hydrolysed by a different enzyme called L-type ThDPase which also hydrolyses nucleoside diphosphates and hence is also known as nucleoside diphosphatase (NDPase, EC 3.6.1.6). It catalyses the hydrolysis of GDP, IDP and UDP, but not ADP. With ThDP, the activity was low at neutral pH but higher at pH 9. 

Fig. 12. Electronmicrograph of rat liver incubated for nucleoside diphosphatase activity. X 62,000. Note reaction product in endoplasmic reticulum (ER) and nuclear membrane (NM) and its absence from mitochondria (M) and nucleolus (N). (Courtesy of Dr. A. B. Novikoff and the Journal of Biological Chemistry. Novikoff and Heus, 1963).

Nucleoside diphosphatase is a characteristic of rat liver microsomes and appears to be bound (Novikoff et al, 1962 NovikoflF and Heus, 1963 NovikoflF and Goldfischer, 1961) to the membranes of the endoplasmic reticulum. The electronmicrograph (Fig. 12) which illustrates this localization is among the first to provide visual evidence of the existence of membrane phosphohydrolases. 

A new finding was the demonstration of nucleoside diphosphatase at cell surfaces and cell membranes (Fig. 13). 

There may, however, be some reason to attribute the origin of the cell membrane nucleoside diphosphatase to the Golgi apparatus as it is involved in the GERL (Golgi-endoplasmic reticulum-lysosomes) structure... 

Circumstantial evidence seems to link at least one phosphohydrolase activity with glucuronyltransferase. Thus, Pelletier and Novikoff (1972) have found that a common feature of the 13 cell types which possess nucleoside diphosphatase activity is the presence of glucuronyltransferase. 

It is likewise of equal interest that the Golgi apparatus is the site of many hydrolase activities such as alkaline and acid phosphatases, j8-glu-curonidase, nucleoside diphosphatase, and thiamine pyrophosphatase. 

Gao XD, Jigami Y. Yeast YNDl gene encodes a new nucleoside diphosphatase required for maturation of N- and O-glycosylation. Glycohiology 1997 7 1044. 

There is a recent, detailed account of methods for preparing and characterizing the components of the endoplasmic reticulum (DePierre and Dallner, 1976). Table 2 lists a number of enzymes associated with the endoplasmic reticulum. Several of these enzymes have been localized to the cytoplasmic surface of the reticular membranes, including cytochrome NADH-cytochrome bs-reductase, Mg " -ATPase, 5 -nucleotidase, nucleoside pyrophosphorylase, and GDP-mannosyl transferase. A number of others, including nucleoside diphosphatase, glucose-6-phosphatase, acetanilide-hydrolyzing esterase, and -glucuronidase have been localized to the luminal surface (DePierre and Ems-ter, 1977). Cytochrome P-450 appears to be present at both the cytoplasmic and luminal surfaces. 

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