¹²⁵I-labeled peptides

For the receptor studies biologically active peptides with very high specific activities are needed. As amino acid tyrosine is very often present in the peptide chain, the introduction of carrier-free radioactive iodine by electrophilic aromatic substitution on activated tyrosine benzene ring is very convenient way to achieve specific activities over 1 000 Ci/mmol of peptide. We have developed iodination methodology based on use of eppendorf micro tubes coated with IODO-GENE™ as oxidation agent. The use of low excess of oxidizing agent and adjusting of the sequence of mixing of reagents enables us to obtain fair to good yields even with oxidation sensitive peptides. The resulting reaction mixture of the starting peptide and its monoiodinated and diiodinated derivatives is separated using radio-HPLC. Some labeled peptides prepared on regular basis are: [¹²⁵I]CART(61-102), [¹²⁵I]prolactin-releasing peptide 31, [¹²⁵I]ghrelin, [¹²⁵I]peptide YY.

³H-labeled compounds

Tritium is the most versatile radionuclide in chemical and biochemical research. Therefore a new and sophisticated tritium labeling technologies are constantly required for the incorporation of tritium into molecules of biological importance as biochemicals and pharmaceuticals. Small molecule drug development stays in the forefront, and isotopic labeling is a vital tool in this process.

We provide syntheses on demand of the commercially non-available labeled compounds . The identity and purity of all prepared labeled compounds is routinely checked by radio-HPLC and by ³H NMR spectroscopy. Our capacity was remarkably enhanced by the installation of our own tritiation facility (tritium manifold in glove box).

¹⁴C-labeled compounds

We started the syntheses of ¹⁴C-labeled compounds in our recently refurbished laboratories by the synthesis of 6-amino-5-nitroso-[6-¹⁴C]uracil and 5-acetyl-6-amino-1,3-dimethyl-[6‑¹⁴C]uracil for the group of Biochemical Pharmacology of Antimetabolites of IOCB. The common commercially available ¹⁴C precursor was used for both compounds - potassium [¹⁴C]cyanate.