Scientists trying to understand how life arose on Earth may never achieve their goal. But their quest is reaping its own reward.
The principles, processes, and chemical effects involved are turning out to have practical relevance today. Earlier this month, for example, Science magazine carried a report by a research team at the University of Georgia in Athens and the California Institute of Technology in Pasadena describing a heat-resistant enzyme that typifies presumed early-life chemistry. Enzymes are proteins that help biochemical reactions go. This one came from an organism that thrives at 100-degree C. temperatures near volcanic vents on the sea floor.
This is the first time the structure of such an enzyme has been deciphered. Commenting on this, Georgia biochemist Michael Adams noted that ''many scientists now support the notion that the Earth's early enzymes functioned at these high temperatures.'' This is one of 20 enzymes Dr. Adams and his colleagues have isolated from the heat-loving organisms so far.
Knowledge of their chemistry may lend a little insight into how Earth's early life evolved. And Adams observes that high-temperature enzymes should also be useful in industry. Unlike most biochemical enzymes, they remain effective even at boiling temperatures. This may lead to improved processes for converting corn starch to sweeteners or to enzyme-based stain-removers, among other things.
Fundamentally, the effort to understand life's origin on Earth is about learning how simple chemicals can self assemble into complex structures and how complex molecules can replicate themselves. It is the search for the principles by which DNA molecules that carry genetic code can reproduce and how DNA and proteins arose.
Last month, early-life chemists Anthony Keefe, Gerald Newton, and Stanley Miller at the University of California in San Diego reported a small step in gaining such knowledge. Earth's early enzymes needed another type of molecule -- a so-called coenzyme -- to do their work. Dr. Miller and his colleagues reported in Nature magazine how they finally have shown that this coenzyme can assemble itself from materials believed to be present in Earth's early oceans. ''Their experiments show that this biologically active molecule could plausibly have formed at the margin of drying pools and lagoons,'' biochemist James P. Ferris of Rensselaer Polytechnic Institute in Troy, N.Y., corroborates.
Here again, a little insight is gained into the chemistry that might have facilitated the rise of earthly life. But the principles of self-assembly that such experiments explore have larger implications. They are opening the way to a new kind of industrial chemistry. That's why researchers in several countries, such as Julius Rebek Jr. at the Massachusetts Institute of Technology in Cambridge, Mass., are pursuing these principles.
Dr. Rebek -- who has demonstrated the self assembly of chemical structures such as proteins and enzymes in a number of experiments -- has explained that he wants to go beyond what may have been involved in life's evolution. He notes that the self replication and self assembly by which these molecules operate apply to many chemical structures. They could give rise to a different, more efficient kind of chemical syntheses than chemists have used up to now.
Chemists in this field are beginning to think more like biologists. The DNA and proteins we know today evolved because they were the most effective molecules in life processes. It was Darwinian survival of the fittest. Chemists are beginning to look to similar Darwinian competition among self-assembling molecules in the laboratory as a way to create new industrial chemicals.
This marriage of biology and traditional laboratory chemistry is giving research chemists a new way to approach their work. As they gain a better grasp of the principles involved, they may also gain new understanding of how life itself might have arisen.
Knowledge of Earth's early high-temperature enzymes may lend insight into how Earth's early life evolved. And such chemicals should also be useful in industry.