Published by the MIT News Office at the Massachusetts Institute of Technology, Cambridge, Mass.
PRIMITIVE LIFE Self-Reproducing Molecules Reported by MIT Researchers By Eugene F. Mallove News Office A significant step toward understanding the origin of life may have been made by a group of MIT researchers. Led by Professor Julius Rebek, Jr. of the Department of Chemistry, they have created an extraordinary self- replicating molecular system that they say might be regarded as a "primitive sign of life." It is not life itself, of course, but it is a kind of molecular model of how self-replication�a most fundamental life process�can occur. In work recently reported in the Journal of the American Chemical Society, Professor Rebek and his coworkers, Tjama Tjivikua, a graduate student from Namibia, and Pablo Ballester, a visiting scientist from the University of Palma in Mallorca, Spain, described the creation of an extraordinary self-replicating molecular system. Ordinarily, it takes the complex biochemical machinery of a cell to reproduce protein molecules. The building blocks of life simply don't replicate themselves by themselves they need help�lots of it�from enzymes and above all from information carried in DNA and RNA. How the whole business of molecular replication got started has been and remains one of the central mysteries of the origin of life. The origin of life is a classic "chicken-and-egg" dilemma. In the presumed molecular evolution on primitive Earth, what came first, proteins or the nucleic acids RNA and DNA? And remember that the enzymes necessary to make proteins are themselves proteins, where did they come from? Amazingly, the laboratory-made molecule that Professor Rebek and his colleagues have created can reproduce itself without the "outside" assistance of enzymes. As such, and because of its specific constitution, the molecule embodies some of the "template" qualities of a nucleic acid, and some of the structural qualities of a protein. The researchers say in their paper, "At best, this can be regarded as a primitive sign of life; at the very least, the system offers a bridge between the information of nucleic acids and the synthesis of amide bonds. It should be possible to design systems capable of peptide [protein] synthesis on a nucleic acid backbone and thereby provide models for events that occurred some time ago." That "some time ago"�in case you missed it in the understated scientific prose�is four billion years ago on primitive Earth. Technically, the self-replicating compound made by the MIT group is called an amino adenosine triacid ester (AATE). This molecule was initially formed by reacting two other molecules. [ The AATE replicates by attracting to one of its ends anester molecule, and to its other end an amino adenosine molecule. These molecules react to form another AATE. The "parent" and "child" AATE molecules then break apart and can go on to build still more AATE molecules. Professor Rebek's research is a continuation of work he began at the University of Pittsburgh. Professor Rebek has been on the MIT faculty since the spring of 1989. His work is supported by the National Science Foundation.
