CRB routinely uses the radioisotopes Tritium and Carbon-14 for the labelling of peptides, whereas Iodine-125 is used for labelling of proteins and antibodies via iodination of tyrosine residues. Tritium and Carbon-14 allow for labelling at high specific activities without compromising the biological activity of the peptide.
Tritium | Carbon-14 | Iodine-125 | |
---|---|---|---|
Common specific activity range | 10-100Ci/matom | 50-100mCi/matom | 2170Ci/matom |
Half life | 12.3 years | 5730 years | 60 days |
Residues frequently labelled | Proline, leucine, tyrosine, phenylalanine, alanine | Glycine, N-acetyl | Tyrosine |
Energy of ß-particle | max 18.6keV mean 5.7keV |
max 156keV mean 49keV |
electron capture |