A simple sequential model is developed which is applicable to the kinetics of melting of some types of oligomeric helices and as an idealization to the kinetics of unfolding of some protein molecules. A procedure is presented for calculating the concentrations of all conformational species as functions of time. The time course of experimentally observable quantities which depend on these concentrations may then be computed.
One of the most characteristic features of the model is the distinction between a transient and a steady-state phase. During the latter all molecular parameters change a t the same rate, which depends strongly on the difficulty of nucleation and the length of the sequence. Simple approximations to the steady-state rate are discussed in terms of the exact solution. Rates of transient processes depend less strongly on the rate of nucleation and the number of steps and are a more direct reflection of the rates of the elementary process of propagation. The value of experimental observation of transient process is emphasized. @ 1972 by John Wiley I % Sons, Inc.
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* When applied to block copolymer helices the successive steps of the model refer to the melting of successive base pairs or peptide residues in the helix. However, when applied to the unfolding of protein molecules, the sequence of steps cannot be related a priori to structural features of the molecule.