Kinetics of the renaturation of yeast tRNA3 leu

Hawkins, E.R.; Chang, S.H.; Mattice, W.L.

Biopolymers 16(7): 1557-1566


ISSN/ISBN: 0006-3525
PMID: 328070
DOI: 10.1002/bip.1977.360160714
Accession: 068526350

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Yeast tRNA3Leu is one of several tRNA molecules which can adopt a stable, biologically inactive, denatured conformation. The circular dichroism of the native and denatured conformers differs, providing the basis for the present study of mechanism for the renaturation process. Conversion of the denatured structure to the native takes place in 2 steps: a rapid change occurring immediately on addition of Mg2+, followed by a slower, strongly temperature-dependent step which returns the molecule to its biologically active state. Optimal kinetic data for the 2nd step was obtained at 285 nm. Analysis of the time dependence of .DELTA.epsilon.285 by the Guggenheim method demonstrated that this step follows 1st-order kinetics. The temperature dependence of the rate constants over the range C yielded the following parameters for the rate-limiting step: Ea = 69 kcal/mole, .**GRAPHIC**. = 69 kcal/mole, and .**GRAPHIC**. = 146 cal/mol degree. Values of this magnitude are typical of order-order transitions in nucleic acids.