Nucleic Acids Research, 2003, Vol. 31, No. 7 e34
© 2003 Oxford University Press
Internal 32P-labeling of L-deoxyoligonucleotides
NOXXON Pharma AG, Max-Dohrn-Strasse 8–10, D-10589 Berlin, Germany
The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors
A general two step procedure for the internal labeling of L-deoxyoligonucleotides, Spiegelmers, has been developed. Through radioactive labeling oligonucleotides can easily be detected and monitored in biological samples. T4 polynucleotide kinase is shown to efficiently phosphorylate strands of L-nucleic acids which allows the labeling with phosphorous isotopes such as 32P. In order to protect the terminal phosphate label against unspecific phosphatases, one of two fragments of a Spiegelmer is enzymatically phosphorylated with [
-32P]ATP. In a second step we used a template- directed chemical ligation reaction in order to attach the labeled oligonucleotide to the other fragment to yield the full-length Spiegelmer with an internal [32P]phosphodiester bond. It has been shown that the functionality of a chemically ligated Spiegelmer is still retained.