TELOMERASE FROM HUMAN LEUKEMIA-CELLS - PROPERTIES AND ITS INTERACTIONWITH DEOXYNUCLEOSIDE ANALOGS

Telomerase is a unique reverse transcriptase involved in the maintenan ce of genomic integrity. In an attempt to understand the properties of this enzyme and to study the effect of deoxynucleoside analogues, we have isolated and partially purified telomerase from the blast cells o f a patient with acute myelogenous leukemia. During the course of puri fication of telomerase, three characteristic forms of this enzyme acti vity were separated. Two processive forms and one less processive form were noted, All forms of the enzyme activities could be abolished by RNase A and proteinase Ii treatments, implying that they are ribonucle oproteins, The major form of telomerase was characterized with respect to divalent ion requirements, effect of salt and nonionic detergents. The K-m of deoxynucleoside triphosphates was determined with a modifi ed telomerase repeat array protocol assay. Studies with deoxynucleosid e analogues indicated that 3'-azido-3'deoxythymidine triphosphate is m uch more inhibitory than 2',3'-dideoxy 2',3'didehydrothymidine triphos phate, and the cytidine analogue ddCTP was not inhibitory. ddGTP was t he most potent inhibitor among all dideoxynucleosides studied.