Calorimetric Investigations on Thermal Stability of tRNAIle (Yeast) and tRNASer (Yeast)

Abstract

Variation with temperature of the partial heat capacities of tRNAIle (yeast) and tRNASer (yeast) has been determined in two buffers at various salt conditions by scanning microcalorimetry. The overall molar transition enthalpy, ΔHt= 320 ± 20 kcal mol−1 (1339 ± 84 kJ mol−1) is identical for the two tRNA species within the limits of experimental error. ΔHt does not show any dependence on the nature of the buffer, nor does' it vary on addition of 1 mM MgCl2 or 150 mM NaCl. Thermal unfolding of the native structure to the random coil cannot adequately be described by a two‐state, concerted transition under the experimental conditions applied in this study, but exhibits a multistep mechanism characterized by sequential unfolding of separable cooperative domains. Copyright © 1976, Wiley Blackwell. All rights reserved