5 -nucleotidases and

As for the stingray venom, not much is known. There was a report on the presence of 5 -nucleotidase and phosphodiesterase in stingray, Urolophus halleri, venom (29). 

Buc HA, Kaplan JC. 1978. Red-cell pyrimidine 5 -nucleotidase and lead poisoning. Clin Chim Acta 87 49-55. 

Paglia DE, Valentine WN, Dahigren JG. 1975. Effects of low-level lead exposure on pyrimidine 5 -nucleotidase and other erythrocyte enzymes Possible role of pyrimidine 5 -nucleotidase in the pathogenesis of lead-induced anemia. J Clin Invest 56 1164-1169. 

The biosynthesis of adenosine is theoretically controlled by several processes namely (1) the biosynthesis of adenosine from AMP by 5 -nucleotidase [EC 3.1.3.5], (2) from S-adenosyl homocysteine by S-adenosyl homocystine hydrolase [EC 3.3.1.1], (3) the metabolism of adenosine to AMP by adenosine kinase [EC 2.7.1.20], and (4) to inosine by adenosine deaminase (ADA) [EC 3.5.4.2], Interestingly, both 5 -nucleotidase and ADA activities were found to be highest in the leptomeninges of rat brain in contrast, the adenosine kinase activity was widely distributed throughout the brain parenchyma, which has negligible ADA activity... 

Certain enzymes shown to be present in myelin could be involved in ion transport. Carbonic anhydrase has generally been considered a soluble enzyme and a glial marker but myelin accounts for a large part of the membrane-bound form in brain. This enzyme may play a role in removal of carbonic acid from metabolically active axons. The enzymes 5 -nucleotidase and Na+, K+-ATPase have long been considered specific markers for plasma membranes and are found in myelin at low levels. The 5 -nucleotidase activity may be related to a transport mechanism for adenosine, and Na+, K+-ATPase could well be involved in transport of monovalent cations. The presence of these enzymes suggests that myelin may have an active role in ion transport in and out of the axon. In connection with this hypothesis, it is of interest that the PLP gene family may have evolved from a pore-forming polypeptide [9],... 

Bottazzi, V. and Premi, L. 1977. Relation between 5 -nucleotidase and agglutination of fat globules. Sci. Tech. Lattiero-Casearia 28, 7-15. (Italian)... 

After purine nucleotides have been converted to the corresponding nucleosides by 5 -nucleotidases and by phosphatases, inosine and guanosine are readily cleaved to the nucleobase and ribose-1-phosphate by the widely distributed purine nucleoside phosphorylase. The corresponding deoxynucleosides yield deoxyribose- 1-phosphate and base with the phosphorylase from most sources. Adenosine and deoxyadenosine are not attacked by the phosphorylase of mammalian tissue, but much AMP is converted to IMP by an aminohydrolase (deaminase), which is very active in muscle and other tissues (fig. 23.20). An inherited deficiency of purine nucleoside phosphorylase is associated with a deficiency in the cellular type of immunity. 

Tomokuni K, Ogata M. 1980. Comparative study of effects of lead on the activity of erythrocyte pyrimidine 5 -nucleotidase and delta-aminolevulinate dehydratase in vivo and in vitro. Arch Toxicol 45 197-201. 

Tomokuni K, Ogata M. 1980. [In-vitro effect of heavy metals on the activity of pyrimidine 5 nucleotidase and gamma amino levulinate dehydratase in the human erythrocyte], Jap J Ind Health 22 282- 283. (Japanese). 

Alkaline phosphatase, acid phosphatase, 5 -nucleotidase, monoacyl hydrolase, ribonuclease, type 1 phosphodiesterase, adenosine triphosphatase, adenyl cyclase, glycosyl transferase, esterases and disaccharidase have been biochemically or cytochemically demonstrated in the tegument of various cestodes (152, 210, 250, 374, 491, 620, 624-626, 651, 718, 763, 776, 898). Several of these enzymes - phosphatases, 5 -nucleotidase and phosphodiesterase - probably have a digestive and/or absorptive function but the role of the others is uncertain. 

Walseth et al. (W3) separated 5 -ribonucleoside monophosphates using ion-pair chromatography. The chromatognq>hic system has been used to analyze tissue nucleotides, to purify nucleoside monophosphates and cyclic nucleotides, and to monitor enzymatic reactions involving cyclic nucleotide phosphodiesterase, 5 -nucleotidase, and adenylate cyclase. 

B-7) (B-7) Pyrimidine S -nucleotidase deficiency. RNA, in this condition, can not be completely degrad in maturing red blood cells. The nucleotides of uridine and cytidine accumulate. This is associated with a hemolytic anemia. In lead poisoning, lead inhibits 5 -nucleotidase and a1.< o mav result in an atieojia. In both... 

The term enzymatic markers of cholestasis (or cholestasis-indicating enzymes) comprises alkaline phosphatase, leucine aminopeptidase (or leucine arylamidase) as well as 5 -nucleotidase and y-glutamyl transferase, (see chapter 13)... 

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