A model for proto-tRNA loading

A kinetic model for loading of proto-tRNA is presented. The kinetic paramet ers were first estimated from the results of Francklyn & Schimmel (1989; Na ture 337, 478-481), who studied the aminoacylation of both tRNA and its min ihelix. Then these parameters were reduced several-fold, as is more appropr iate for the prebiotic world. The simulations revealed a very slow time cou rse of the loading reaction. We also consider a possibility for the proto-t RNA loading without a catalyst and discuss the feasibility of such processe s. Analytical approximations are presented for the kinetics of proto-tRNA l oading with and without enzyme. An estimate is given for the time required for the development of template- and sequence-directed systems. (C) 2001 Ac ademic Press.