[125I] Radioiodination

Radioiodine ([125I]) is widely used in the preparation of tracers for sensitive immunoassays and other procedures for the detection, localisation and quantification of substances in biological samples, for example, receptor binding assays or autoradiography.

[125I] can be introduced into proteins/peptides either indirectly by conjugating to a ready labelled compound such as [125I]-Bolton & Hunter reagent or directly using a soluble oxidizing agent such as chloramine-T. Indirect or conjugation methods are milder for proteins by avoiding exposure to potentially denaturing conditions during the radiolabelling procedure. Following radiolabelling, the tracer is carefully purified to remove unreacted [125I] and other reaction by-products by specialized methods.

METIS Labs Custom Radioiodination Services offers a wide range of labeling techniques to best maintain the biological activity of your molecule to advance your peptide, protein or antibody development pipeline.

Bolton-Hunter Reagent

Compounds containing Lysine Groups

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Chloramine-T

Molecules containing Tyrosine or Histidine

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[125I]-labeled, Bolton-Hunter

Lactoperoxidase

Compounds containing Tyrosine

[125I]-labeled, Bolton-Hunter

Iodogen®

Molecules containing Tyrosine or Histidine

[125I] Radioiodination

METIS Labs Custom Radioiodination Services offers a wide range of labeling techniques to best maintain the biological activity of your molecule to advance your drug development pipeline.

Bolton-Hunter Reagent – Compounds containing Lysine Groups

Labels terminal amino groups with a radioiodinated phenolic residue, effectively introducing radioactive iodine into proteins and peptides. Since it is a non-oxidative technique, it is “less harsh” to proteins than alternative methods in turn retaining a high degree of binding activity to receptors.

Chloramine-T – Molecules containing Tyrosine or Histidine

Labels peptides and proteins naturally containing, or have been chemically modified, either tyrosine or histidine. Hypochlorite released from chloramine-T acts as an effective oxidizing agent for iodide which undergoes electrophilic substitution to the tyrosine or histidine.

Lactoperoxidase – Compounds containing Tyrosine

Lactoperoxidase catalyzes the oxidation of iodine using hyrdogen peroxide as a substrate. It is a milder oxidative method than Iodogen® and leaves methionine residues intact

Iodogen® – Molecules containing Tyrosine or Histidine

This is an effective method for labeling a variety of proteins and peptides. This oxidative method involves exposure of the substrate to Iodogen® in the presence of sodium [125I]Iodide followed by HPLC or other seperation techniques. It produces high specific activity proteins or peptides in good yields. However, a drawback is that cysteine and methionine residues in the peptide may be partially oxidized during the procedure.

Iodogen® is a registered trademark of Pierce

[125I] Radioiodination

METIS Labs Custom Radioiodination Services offers a wide range of labeling techniques to best maintain the biological activity of your molecule to advance your drug development pipeline.

Bolton-Hunter Reagent – Compounds containing Lysine Groups

Labels terminal amino groups with a radioiodinated phenolic residue, effectively introducing radioactive iodine into proteins and peptides. Since it is a non-oxidative technique, it is “less harsh” to proteins than alternative methods in turn retaining a high degree of binding activity to receptors.

Chloramine-T – Molecules containing Tyrosine or Histidine

Labels peptides and proteins naturally containing, or have been chemically modified, either tyrosine or histidine. Hypochlorite released from chloramine-T acts as an effective oxidizing agent for iodide which undergoes electrophilic substitution to the tyrosine or histidine.

Lactoperoxidase – Compounds containing Tyrosine

Lactoperoxidase catalyzes the oxidation of iodine using hyrdogen peroxide as a substrate. It is a milder oxidative method than Iodogen® and leaves methionine residues intact

Iodogen® – Molecules containing Tyrosine or Histidine

This is an effective method for labeling a variety of proteins and peptides. This oxidative method involves exposure of the substrate to Iodogen® in the presence of sodium [125I]Iodide followed by HPLC or other seperation techniques. It produces high specific activity proteins or peptides in good yields. However, a drawback is that cysteine and methionine residues in the peptide may be partially oxidized during the procedure.

Iodogen® is a registered trademark of Pierce