enzyme: Reverse Transcriptase
NRTIs must be
converted inside the cell to their active form (i.e. phosphorylated
to a nucleoside triphosphate).The NRTIs trick reverse transcriptase
into using the fake nucleoside triphosphates. The virus thinks it
is inserting a natural nucleoside triphosphate into the DNA chain,
but in actual fact it is inserting the drug. When this occurs the
chain of DNA being formed will be prematurely terminated.