Non-nucleoside inhibitors of mitochondrial thymidine kinase (TK-2) differentially inhibit the closely related herpes simplex virus type 1 TK and Drosophila melanogaster multifunctional deoxynucleoside kinase.
5'-O-Trityl derivatives of thymidine (dThd), (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU), and their acyclic analogs 1-[(Z)-4-triphenylmethoxy-2-butenyl]thymine (KIN-12) and (E)-5-(2-bromovinyl)-1-[(Z)-4-triphenylmethoxy-2-butenyl]uracil (KIN-52) have been synthesized and evaluated for their inhibitory activity against the amino acid sequence related mitochondrial dThd kinase (TK-2), herpes simplex virus type 1 (HSV-1) TK, and Drosophila melanogaster multifunctional 2'-deoxynucleoside kinase (Dm-dNK). Several compounds proved markedly inhibitory to these enzymes and represent a new generation of nucleoside kinase inhibitors. KIN-52 was the most potent and selective inhibitor of TK-2 (IC(50), 1.3 microM; K(i), 0.50 microM; K(i)/K(m), 0.37) but was not inhibitory against HSV-1 TK and Dm-dNK at 100 microM. As found for the alternative substrate BVDU, the tritylated compounds competitively inhibited the three enzymes with respect to dThd. However, whereas BVDU behaved as a noncompetitive inhibitor (alternative substrate) of TK-2 and HSV-1 TK with respect to ATP as the varying substrate, the novel tritylated enzyme inhibitors emerged as reversible purely uncompetitive inhibitors of these enzymes. Computer-assisted modeling studies are in agreement with these findings. The tritylated compounds do not act as alternative substrates and they showed a type of kinetics against the nucleoside kinases different from that of BVDU. KIN-12, and particularly KIN-52, are the very first non-nucleoside specific inhibitors of TK-2 reported and may be useful for studying the physiological role of the mitochondrial TK-2 enzyme.
Balzarini
Jan
J
Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, Belgium. jan.balzarini@rega.kuleuven.ac.be
Hernández
Ana-Isabel
AI
Roche
Philippe
P
Esnouf
Robert
R
Karlsson
Anna
A
Camarasa
Maria-José
MJ
Pérez-Pérez
Maria-Jesus
MJ
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D004331:Drosophila melanogaster / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology; D009097:Multienzyme Complexes; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors*; D018139:Simplexvirus / Q000201:enzymology; D013379:Substrate Specificity; D013936:Thymidine / Q000031:analogs & derivatives / Q000494:pharmacology; D013937:Thymidine Kinase / Q000037:antagonists & inhibitors*; D014498:Uracil / Q000031:analogs & derivatives / Q000494:pharmacology
D004791:Enzyme Inhibitors; C471128:KIN-12; C471127:KIN-52; D009097:Multienzyme Complexes; D014498:Uracil; D000255:Adenosine Triphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C020018:deoxyribonucleoside kinases; C105339:thymidine kinase 2; D013937:Thymidine Kinase; C092717:thymidine kinase 1; D013936:Thymidine