COMPUTATIONAL STUDIES OF THE ELECTROWEAK ORIGIN OF BIOMOLECULAR HANDEDNESS IN NATURAL-SUGARS

The violation of parity by the weak interactions ensures that enantiomeric chiral molecules have inequivalent energies. These parity violating energy differences have been calculated, using ab initio methods, for the biologically important sugars deoxyribose, ribose, arabinose, xylose and lyxose. It is found that in each case the choice of which enantiomer is of lower energy is dependent on the molecular conformation adopted, particularly the type of furanose ring pucker. In general the D-enantiomers are favoured for molecules having a C2-endo pucker, whereas the L-series are preferred for C3-endo puckers. The significance of these energy differences for the transition from a prebiotic racemic geochemistry to a homochiral biochemistry in terrestrial evolution is discussed.