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Laser light‐scattering analysis of the dimerization of transfer ribonucleic acids with complementary anticodons
Author(s) -
Wang ChunChen,
Ford Norman C.,
Fournier Maurille J.
Publication year - 1981
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1981.360200111
Subject(s) - chemistry , equilibrium constant , enthalpy , dimer , thermodynamics , diffusion , transfer rna , macromolecule , ionic strength , aqueous solution , rna , organic chemistry , biochemistry , physics , gene
Photon‐correlation spectroscopy is a powerful technique for measuring the translational diffusion coefficient of particles and macromolecules in solution. In the study described here, this technique was used to analyze a specific dimerization process involving the association of two tRNA molecules through complementary anticodons. The tRNAs used in the analysis were E. coli tRNA 2 Gluand yeast tRNA Phe . The experimental data on the concentration dependence of the observed diffusion constants are shown to agree well with theoretical predictions. From these data, the equilibrium constant of the association reaction was determined for dimers formed over a wide range of temperatures and in several different solution conditions. In solutions of 0.1 M ionic strength at 22°C, the equilibrium constants vary from 1 × 10 5 M −1 in the absence of magnesium to 1.5 × 10 6 M −1 in 10 m M Mg +2 . The enthalpy and entropy changes for dimer formation in the absence and presence, 5 and 10 m M , of magnesium have been obtained from the temperature dependence of the equilibrium constant. The results show that both Δ H and Δ S contribute to the free energy of binding and that their relative contributions are similar for each solution condition evaluated.