'Binary' enzyme created by TSRI scientists demonstrates Darwinian evolution at it...( s into U and may not have been abundan...)

Odd Base Out

To address this, Nobel Laureate Francis Crick suggested almost 40 years ago that life may have started with two bases instead of four. Now Reader and Joyce have demonstrated that a two-base system is chemically feasible.

Several years ago, Joyce showed that RNA enzymes could be made using only three bases (A, U, and G, but lacking C). The "C minus" enzyme was still able to catalyze reactions, and this work paved the way for creating a two-base enzyme.

In the current study, Reader and Joyce first created a three-base enzyme (A, U, G) and then performed chemical manipulations to convert all the A to D (diaminopurine, a modified form of A) and biochemical manipulations to remove all the G. They were left with an enzyme based on a two-letter code (D and U).

Reader and Joyce insist that their study does not prove life started this way. It does, however, demonstrate that it is possible to have a genetic system of molecules capable of undergoing Darwinian evolution with only two distinct subunits.

'"/>

Contact: Keith McKeown
kmckeown@scripps.edu
858-784-8134
Scripps Research Institute
18-Dec-2002