Tethered bisubstrate derivatives as probes for mechanism and as inhibitors of aminoglycoside 3'-phosphotransferases.
Aminoglycoside 3'-phosphotransferases [APH(3')s] phosphorylate aminoglycoside antibiotics, a reaction that inactivates the antibiotics. These enzymes are the primary cause of resistance to aminoglycosides in bacteria. APH(3')-Ia operates by a random-equilibrium BiBi mechanism, whereas APH(3')-IIIa catalyzes its reaction by the Theorell-Chance mechanism, a form of ordered BiBi mechanism. Hence, both substrates have to be present in the active site prior to the transfer of phosphate by both mechanisms. Four bisubstrate analogues, compounds 1-4, were designed and synthesized as inhibitors for APH(3')s. These compounds are made of adenosine linked covalently to the 3'-hydroxyl of neamine (an aminoglycoside) via all-methylene tethers of 5-8 carbons. The K(i) values measured for these compounds indicated that affinities of APH(3')-Ia and APH(3')-IIa for compounds 2 and 3 (six- and seven-carbon tethers, respectively) were the best, and the inhibition constants for the two were comparable.
Liu
M
M
Department of Chemistry and the Institute for Drug Design, Wayne State University, Detroit, Michigan 48202, USA.
Haddad
J
J
Azucena
E
E
Kotra
L P
LP
Kirzhner
M
M
Mobashery
S
S
D002240:Carbohydrate Sequence; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry; D019868:Kanamycin Kinase / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D013379:Substrate Specificity
D004791:Enzyme Inhibitors; D019868:Kanamycin Kinase