Sidney Altman
During experiments in which the complex was taken apart and put together in test tubes, Altman and his group discovered a remarkable thing.  The RNA component, in isolation, was enough for the observed catalytic activity of the enzyme. This was remarkable because, previously, it was thought that only enzymes could catalyse reactions in living cells. Altman's research showed that RNA itself had catalytic properties. This was the discovery that earned him the Nobel prize.