[Spin-lattice-relaxationtime T1 measurements of nucleosides (author's transl)]

Nucleosides and nucleotides have been investigated by means of the spin-lattice-relaxationtime T1, the measurements carried out in CDCl3 on the nucleosides adenosine (A), uridine (U) and inosine (I) indicate that the strength of H-bonding is highest in the basepair (A)--(U). The systems (A)--(A), (U)--(U), (I)--(A) and (I)--(U) however, show only a low tendency to associate. Plotting the spin-lattice-relaxationtime, of the nucleotide protons in fragments (mol weight below 40,000) originated from DNA or RNA, against increasing temperature gives a curve with a sigmoide shape and a Tm value of 80 degrees C. The average of the activation energy for the H-bonding is 18.02 KJ/mol. The investigations clearly show that the spin-lattice-relaxationtime measurements open first of all a new method for research on H-bonding, secondly it is even in the case of nucleosides and oligonucleotides, where most of the common methods fail, a way to get information about H-bonding effects.