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September Newsletter:

Radiolabelling: Radiolabelled Peptides
Piquant Peptides: Pure tritiated peptides
Specific Acitivity: Optimum levels for each radio-isotope

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Radiolabelled Peptides

Cambridge Research Biochemicals (CRB) is the second oldest custom manufacturer of peptides in the world, with 30 years of experience of providing high quality bespoke peptides.

Strategic Alliances

CRB is able to leverage this expertise in peptide synthesis, through unique collaborations with major radio-synthesis groups, to provide peptides and proteins labelled with tritium (3H), carbon-14 (14C) and iodine-125 (125I).

Piquant Peptides

Features of Radiolabelling Service

  • Product shipped directly from the radiochemical laboratory to the customer
  • CRB liaises with shipping broker to ensure smooth and problem free delivery to the customer
  • Trititated Peptides are usually supplied in 10% aqueous ethanol to improve stability
  • Cold reference peptide is made as standard to determine specific activity. Cold peptide can be used as diluent to improve stability of hot peptide
  • Small organic molecules can also be prepared radiolabelled
  • Custom aliquotting upon request

Customer Peptide References

M. Pieri1, H. C. Christian1, R. J. Wilkins1, C. A. R. Boyd1 & D. Meredith2, 1University of Oxford & 2Oxford Brookes University
The apical (hPepT1) and basolateral peptide transport systems of Caco-2 cells are regulated by AMP-activated protein kinase.
Am. J. Physiol. Gastrointest. Liver. Physiol., 2010, 13, 136-143

F. Ötvös, D. S. Gembitsky, R. F. Murphy & S. Lovas, Creighton University School of Medicine
Synthesis and Structure-Activity Relationship of [Nle10]Neurokinin A (4–10) Analogs with Constraint in the Backbone and at Position Six.
Int. J. Pept. Res. Ther., 2007, 13, 329-336

Need to know more?

To order your Radiolabelled Peptides or to learn more about our products visit: www.crbdiscovery.com/technical/radiolabelling or telephone: 01642 567180

  Tritium (3H) labelled Peptides

Pure specifically tritiated peptides can be made for use in receptor studies, metabolic studies and pharmacological investigation.

Tritium reduction by catalytic exchange is the simplest and most economic route for labelling peptides that do not contain Cysteine residues.

Analogues of the peptide containing one or more of Phe, Pro, Tyr, or Leu residues substituted with a double bond or halogen moiety are synthesised at CRB and sent to the radio-synthesis group where these precursor peptides are then reduced with Tritium to generate the desired tritium labelled peptide with a specific activity in the range of 10-100Ci/mmole.

Iodine-125 (125I) labelled Peptides and proteins

Iodine-125, with a half-life of 60 days, is a cost-effective choice for labelling of peptides and proteins, as the reaction is performed directly on the peptide or protein sample. CRB offers a fixed fee service for iodination (2 x 50 mCi[125I]) and HPLC purification. For peptides and proteins containing tyrosine residues, iodination is carried out with Na125I activated with chloramin-T, lactoperoxidase or iodogen. Alternatively, free amino functions of the protein can be labelled using 125I-Bolton-Hunter reagent.

Carbon-14 (14C) labelled Peptides

Carbon-14 should only be considered after Tritium for two reasons: Carbon-14 can only be incorporated in to peptides via an expensive Carbon-14 labelled amino acid or by addition to the N-terminus of the peptide (e.g. 14C-Acetic acid to form 14C-Acetyl-peptide) and secondly due to the thousand-fold reduction in specific activity.


High Specific Activity

Tritium labelling

The simplest route to tritium labelled peptides involves the catalytic hydrogenation or hydrogenolysis of a peptide analogue containing unsaturated or iodinated precursor amino acid derivatives (Figure 1). These peptides are assembled, purified and characterised in the same way as other peptides and then treated with tritium gas to generate the tritium labelled peptide.

125I labelling

Labelling with iodine-125 normally involves incorporation of iodine-125 into tyrosine or histidine residues within the peptide or protein (Figure 2). This is done by treatment of the sample with Na125I in the presence of an oxidising reagent to generate a source of electrophilic iodine. Usually, one or two iodine atoms are added depending on conditions used. For peptides and proteins lacking accessible tyrosine residues, free amines can be derivatised with Bolton-Hunter reagent prior to iodination.

14C labelling

The simplest approach to 14C labelling involves acetylation of free amino groups in the peptide with 14C-acetic acid to provide peptides with a specific activity of up to 120mCi/mmol. Glycine also can be prepared with one or both carbon atoms labelled with carbon-14 leading to a maximum specific activity of 100-120mCi/mmole and incorporated during peptide assembly.

More information

For more information on Piquant Peptides please visit our website or telephone: 01642 567180

CRB will be exhibiting and attending the following exhibitions

EPS More info Proteomics Methods Forum More info
Genesis 2010 More info Genes and Cancer More info

View our full range of products

Visit our website to view our full range of products, we offer products for the following:

Peptides PNA Fluorescent Dyes Immunological

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