Altman, Sidney (1939-...), a Canadian-born American molecular biologist, discovered important properties of a complex molecule called ribonucleic acid (RNA). RNA assists in constructing enzymes (types of protein), a process crucial to the workings of the living cell. Altman discovered that RNA also worked as a catalyst of the cell's chemical processes. A catalyst is a substance that speeds up a reaction without itself being altered. Altman's discovery clarified several problems in biology about the origins of life. Altman was awarded the Nobel Prize in chemistry in 1989, and shared the prize with Thomas Cech who worked independently in the same field. See Cech, Thomas Robert; Cell.