Nucleosidases

Extending the aforementioned methodology from imidazole to adenine, the Tsuji-Trost reaction between the sodium salt of adenine and allylic acetate 66 gave 67 as a 82 18 mixture of cis trans isomers. Carbocyclic nucleoside 67 was advantageous over normal nucleosides as a drug candidate because it was not susceptible to degradation in vivo by nucleosidases and phosphorylases [52],... 

Bacterial electrodes [11, 31, 33, 46, 48, 49, 60] In this type of electrode, a suspension of suitable bacteria is placed between the sensor proper and a dialysis membrane that prevents passage of high-molecular substances (see fig. 8.3). The sensor is usually a gas probe. In the simple types of bacterial electrode, the determinand is converted by a suitable strain of bacteria into a product sensed by the gas probe. Thus it is possible to determine arginine [46], glutamine [48],/.-aspartic acid [31],/.-histidine [60] and nitrate [33]. Hybrid bacterial - enzyme electrodes contain both a bacterial strain and a suitable enzyme. For example, an extract from ivingas Neurospora chossa can be used as a source of NAD nucleosidase and an Escherichia coli culture as a source of nicotinamide deaminase, so that the electrode responds to NAD [49] as a result of the series of reactions... 

The synthesis of 964 was achieved by coupling 6-chloropurine and 4-methylthiobutan-l-ol (962) under the influence of DEAD/PhaP to give 963, followed by ammonolysis to 964 [93JCS(P1)1109], It was a potent inhibitor of the enzyme methylthioadenosine nucleosidase. 

This enzyme [EC 3.2.2.16], also known as methylthioade-nosine nucleosidase, catalyzes the hydrolysis of methyl-thioadenosine to produce adenine and 5-methylthio-D-ribose. S-Adenosylhomocysteine is not a substrate for this enzyme. See also S-Adenosylhomocysteine Nucleosidase... 

This enzyme [EC 3.2.2.5] (also known as NAD+ nucleosidase, NADase, DPNase, DPN hydrolase, and ADP-ribo-sylcyclase) catalyzes the hydrolysis of NAD+ to nicotinamide and ADP-ribose. The enzyme from some mammalian sources also catalyzes the transfer of ADP-ribose residues. 

NADH PEROXIDASE NADH PEROXIDASE NAD KINASE NAD nucleosidase,... 

PULSE-CHASE EXPERIMENTS N-END RULE PULSE RADIOLYSIS PURINE NUCLEOSIDASE PURINE NUCLEOSIDE PHOSPHORYLASE PUTRESCINE CARBAMOYLTRANSEERASE PUTRESCINE N-METHYLTRANSEERASE PUTRESCINE OXIDASE Putrescine synthesis,... 

J. A. Gutierrez, T. Crowder, A. Rinaldo-Matthis, M.-C. Ho, S. C. Almo, and V. L. Schramm, Transition state analogs of 5 -methylthioadenosine nucleosidase disrupt quorum sensing, Nat. Chem. Biol., 5 (2009) 251-257. 

DC085 Han, A., K. P. Zanewich, S. B. Rood, and D. K. Dougall. Gibberellic acid decreases anthocyanin accumulation DC095 in wild carrot cell suspension cultures but does not alter 3 nucleosidase activity. Physiol Plant 1994 92(1) ... 

Under approximately these same conditions, PPt is hydrolyzed approximately two-thirds as rapidly as glucose-6-P (98). The rates of hydrolysis of nucleosidetriphosphates and diphosphates have not been adequately assessed because of contamination of microsomal preparations with additional nucleosidases (41, 124)-... 

Fig. 1. Ethylene biosynthesis. The numbered enzymes are (1) methionine adenosyltransferase, (2) ACC (l-aminocyclopropane-l-carboxylic acid) synthase, (3) ethylene forming enzyme (EFE), (4) 5 -methylthio-adenosine nucleosidase, (5) 5 -methylthioribose kinase. Regulation of the synthesis of ACC synthase and EFE are important steps in the control of ethylene production. ACC synthase requires pyridoxal phosphate and is inhibited by aminoethoxy vinyl glycine EFE requires 02 and is inhibited under anaerobic conditions. Synthesis of both ACC synthase and EFE is stimulated during ripening, senescence, abscission, following mechanical wounding, and treatment with auxins.

Lampen (see Ref. 56) had prepared a 1-D-ribosylthymine from thymine plus D-ribosyl phosphate in the presence of nucleosidases from Escherichia coli B. 

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