Open AccessDetermination of the Activation Energy for Pseudorotation of the Furanose Ring in Nucleosides by 13 C Nuclear‐Magnetic‐Resonance Relaxation
Author(s) -
RÖDER Oskar,
LÜDEMANN HansDietrich,
GOLDAMMER Eberhard
Publication year - 1975
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1975.tb04094.x
Subject(s) - furanose , inosine , chemistry , pseudorotation , guanosine , cytidine , uridine , activation energy , hydroxymethyl , ring (chemistry) , adenosine , cytosine , relaxation (psychology) , guanine , stereochemistry , nucleotide , organic chemistry , rna , biochemistry , enzyme , dna , gene , social psychology , psychology
The activation energies for the pseudorotation of the furanose ring in adenosine, guanosine, inosine and xanthosine dissolved in liquid deuteroammonia have been determined by analysis of the longitudinal relaxation rates of the single tertiary carbons between + 40 °C and –60 °C. For the purine ribosides the average activation energy was found to be 4.7 ± 0.5 kcal ± mol −1 (20 ± 2 kJ ± mol −1 ). For the pyrimidine nucleosides cytidine and uridine the respective activation energy should be higher since it could not be determined by 13 C relaxation measurements. This result can be explained by the formation of a hydrogen bond between the 5′‐hydroxymethyl group and the base. In adenosine, guanosine, inosine and xanthosine the relaxation rates of C(5′) are smaller than all others thus excluding the formation of a hydrogen bond between the purine base and the 5′‐hydroxymethyl group of a strength comparable to the one suggested for cytidine and uridine.