Thermal transitions in E. coli tRNAfMet and two of its molecular fragments

N. R. Kallenbach, R. I. Ma, J. Ofengand, M. A.Q. Siddiqui

Research output: Contribution to journalArticlepeer-review


Melting curves of tRNAfMet and two fragments derived from this molecule by limited ribonuclease T1 digestion (i.e., the anticodon arm and loop [K fragment] and the larger fragment representing three‐fourths of the tRNA chain from the 3′ terminus including two potential limbs of the cloverleaf structure [L fragment]) are presented. The profiles observed are consistent with the presence of base paired structures in all those molecules. At low salt concentration (0.02M Na+) the stabilities of these molecules measured by the apparent midpoints of the denaturation profiles are in the order K > L > tRNA. The relative stabilities approach each other at 0.2M Na+ (the tRNA profile being biphasic), while at high salt (2M) the L fragment seems to be more stable than either K or t‐RNA fMet. Estimation of the enthalpy of denaturing the K structure in 0.02M Na+ gives a value of 40 ± 3 kcal/mole corresponding to an enthalpy per effective G.C. base pair disrupted of 10 ± 1 kcal/mole.

Original languageEnglish (US)
Pages (from-to)1247-1257
Number of pages11
Issue number6
StatePublished - Jun 1973

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Biomaterials
  • Organic Chemistry


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