[TAISM2000]

What is the suggested procedure to label any peptide with radioisotope

[gippgig]

What kind of label?
Are you referring to synthesizing a labeled peptide? Labeling a naturally produced peptide in an organism? Labeling an existing peptide?

[TAISM2000]

Labeling an existing peptide.

[gippgig]

The simplest thing is to react the peptide with a labeled compound that will covalently bond to it. For example, if you have labeled acetate, you could acetylate the N-terminus (assuming it isn't blocked) the same way (taking whatever radiation handling precautions are warranted) you would acetylate it with unlabeled acetate. Of course, this would change both the chemical & biological properties of the peptide.

[TAISM2000]

Thank you for this clarification.

I am trying to label Leptin with Indium - 111.

Lipten =  MHWGTLCGFLWLWPYLFYVQAVPIQKVQDDTKTLIKTIVTRINDISHTQSVSSKQKVTGLDFIPGLHPIL
TLSKMDQTLAVYQQILTSMPSRNVIQISNDLENLRDLLHVLAFSKSCHLPWASGLETLDSLGGVLEASGY
STEVVALSRLQGSLQDMLWQLDLSPGC

Any particular protocol/method.

Thank you for your help