Stereoelectronic effects in RNase-catalysed reactions of dinucleoside phosphate cleavage

AbstractThe rate at which dinucleoside phosphates are cleaved by RNases is supposed to be determined by the mole fraction of enzyme-substrate complexes in which the phosphodiester moiety of a dinucleoside phosphate has a highly reactive conformation. The mole fraction of such complexes for a particular RNase depends on the nature of a nucleoside at the O5'-end of the phosphodiester bond. Experimental data are presented to support this hypothesis

Correlative variations of the free energies for enzyme-substrate complex formation and the transition-state stabilization for RNases

AbstractIt was found for RNases of different specificities that changes in the free energy for substrate-enzyme binding induced by variations in the nucleotide base structure are accompanied by proportional changes in kcat/Km. This was considered to be a consequence of the strain in the enzyme-substrate complex