Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.4.4 (adenosine deaminase)
 5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of adenine nucleosides with exocyclic double bonds either at the 4',5' position in pentofuranosyl nucleosides or at the 5',6' position of hexofuranosyl nucleosides have been found to act as substrates for adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) from calf intestinal mucosa. Most of the results obtained are contrary to the accepted minimal structural requirements for substrate activity. These nucleosides had either incorrect anomeric configurations or no hydroxyl group at C-5' or C-3' in the proper configuration; some compounds incorporated both structural changes. There is a possiblity that the unsaturated group has a special role in binding to the enzyme.
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PMID:Unusual substrates for adenosine deaminase from calf intestinal mucosa. 68 43

The synthesis and biological evaluation of three classes of chain-modified derivatives of (+)-EHNA are described. Among the 5', 6'-unsaturated derivatives, the Z-isomer was the most potent inhibitor of adenosine deaminase (ADA) but 3-fold less active than (+)-EHNA. Several 9-aralkyladenines (ARADs) have been prepared, and their inhibitory activity was determined. A minimum of two carbon atoms separating the aromatic ring from the adenine-bearing carbon (C-3') was found to be essential for ADA activity equal to or slightly greater than that of (+)-EHNA. Finally, replacement of the C-5' carbon with an oxygen resulted in reduced potency.
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PMID:Adenosine deaminase inhibitors: synthesis and biological evaluation of unsaturated, aromatic, and oxo derivatives of (+)-erythro-9-(2'S-hydroxy-3'R-nonyl)adenine [(+)-EHNA]. 1110 60

Nucleos(t)ide reverse transcriptase inhibitors (NRTIs) form the backbone of most anti-HIV therapies. We have shown that 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a highly effective NRTI; however, the reasons for the potent antiviral activity of EFdA are not well understood. Here, we use a combination of structural, computational, and biochemical approaches to examine how substitutions in the sugar or adenine rings affect the incorporation of dA-based NRTIs like EFdA into DNA by HIV RT and their susceptibility to deamination by adenosine deaminase (ADA). Nuclear magnetic resonance (NMR) spectroscopy studies of 4'-substituted NRTIs show that ethynyl or cyano groups stabilize the sugar ring in the C-2'-exo/C-3'-endo (north) conformation. Steady-state kinetic analysis of the incorporation of 4'-substituted NRTIs by RT reveals a correlation between the north conformation of the NRTI sugar ring and efficiency of incorporation into the nascent DNA strand. Structural analysis and the kinetics of deamination by ADA demonstrate that 4'-ethynyl and cyano substitutions decrease the susceptibility of adenosine-based compounds to ADA through steric interactions at the active site. However, the major determinant for decreased susceptibility to ADA is the 2-halo substitution, which alters the pKa of N1 on the adenine base. These results provide insight into how NRTI structural attributes affect their antiviral activities through their interactions with the RT and ADA active sites.
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PMID:Effects of substitutions at the 4' and 2 positions on the bioactivity of 4'-ethynyl-2-fluoro-2'-deoxyadenosine. 2410 Apr 93