Antisense principle or ribozyme action?

When incorporated into long stretches of antisense RNA, the catalytic domain of the hammerhead type ribozyme significantly increases the extent of antisense-mediated inhibition in living cells. A kinetic model based on the rate constants determined for duplex formation and cleavage of target RNA in vitro is not compatible with the observed biological effects and indicates that further assumptions have to be included to explain the action of ribozymes in vivo.