Discovery of type II (covalent) inactivation of S-adenosyl-L-homocysteine hydrolase involving its "hydrolytic activity": synthesis and evaluation of dihalohomovinyl nucleoside analogues derived from adenosine.
Treatment of the 5'-carboxaldehyde derived by Moffatt oxidation of 6-N-benzoyl-2',3'-O-isopropylideneadenosine (1) with the "(bromofluoromethylene)triphenylphosphorane" reagent and deprotection gave 9-(6-bromo-5, 6-dideoxy-6-fluoro-beta-d-ribo-hex-5-enofuranosyl)adenine (4). Parallel treatment with a "dibromomethylene Wittig reagent" and deprotection gave 9-(6,6-dibromo-5, 6-dideoxy-beta-d-ribo-hex-5-enofuranosyl)adenine (7), which also was prepared by successive bromination and dehydrobromination of the 6'-bromohomovinyl nucleoside 8. Bromination-dehydrobromination of the 5'-bromohomovinyl analogue 11 and deprotection gave (E)-9-(5, 6-dibromo-5,6-dideoxy-beta-d-ribo-hex-5-enofuranosyl)adenine (15). Compounds 4, 7, and 15 were designed as putative substrates of the "hydrolytic activity" of S-adenosyl-l-homocysteine (AdoHcy) hydrolase. Enzyme-mediated addition of water across the 5,6-double bond could generate electrophilic acyl halide or alpha-halo ketone species that could undergo nucleophilic attack by proximal groups on the enzyme. Such type II (covalent) mechanism-based inactivation is supported by protein labeling with 8-[3H]-4 and concomitant release of bromide and fluoride ions. Incubation of AdoHcy hydrolase with 7 or 15 resulted in irreversible inactivation and release of bromide ion. In contrast with type I mechanism-based inactivation, reduction of enzyme-bound NAD+ to NADH was not observed. Compounds 4, 7, and 15 were not inhibitory to a variety of viruses in cell culture, and weak cytotoxicity was observed only for CEM cells.
Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602-5700, USA.
S F
SF
Wnuk
Y
Y
Mao
C S
CS
Yuan
R T
RT
Borchardt
G
G
Andrei
J
J
Balzarini
E
E
De Clercq
M J
MJ
Robins
D043383:Adenosylhomocysteinase; D000998:Antiviral Agents / Q000138:chemical synthesis / Q000494:pharmacology; D002461:Cell Line, Transformed; D016048:Dideoxyadenosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000494:pharmacology; D006801:Humans; D006867:Hydrolases / Q000037:antagonists & inhibitors*; D006868:Hydrolysis; D008826:Microbial Sensitivity Tests; D010920:Placenta / Q000201:enzymology; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors
C113652:9-(5,6-dibromo-5,6-dideoxyhex-5-enofuranosyl)adenine; C113651:9-(6,6-dibromo-5,6-dideoxyhex-5-enofuranosyl)adenine; C113650:9-(6-bromo-5,6-dideoxy-6-fluorohex-5-enofuranosyl)adenine; D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D016048:Dideoxyadenosine; D006867:Hydrolases; D043383:Adenosylhomocysteinase