Re: Iodination of peptides

Roger Murphy (murphy_r@licre.ludwig.edu.au)
Wed, 14 Oct 1998 09:54:01 +1000

At 02:57 PM 13-10-98 -0400, you wrote:
>I was wondering if someone could give me some insight on the possible
>iodination of tyrosine. I have been trying to iodinate my protein with cold
>iodine. I have been using Pierce's iodogen coated tubes to iodinate my
>protein. For a positive control I have been using Angiotension III
>(RVYIHPF). The first and only time I tried this Angio III increased in mass
>by 503.58 this seems to indicate 4 iodine's were added. Is this possible?
>Were they all added to the tyrosine, or can they be added to other amino
>acids as well?
>
>Thanks a lot in advance
>
>
>__________________________________
>Brett Phinney
>North Carolina State University
>Department of Biochemistry
>Ph# 919-515-5786, Fax 919-515-2047
>ICQ# = 12442943
>

Brett,

I've used the Iodogen method a lot, and the extent of iodination of the Tyr
depends on the length of time you leave it in contact with the agent.
Di-iodination is not uncommon. I believe the kinetics of iodination are
such that the 2nd iodine zips on faster. Also, depending upon the pH of
your reaction solution, iodination of His can also occur. Indeed, I've
used this to iodinate peptides that contained His but no Tyr for RIAs.
Hope this helps.

Cheers,

Roger

Roger Murphy, Ph.D.
Biological Production Facility
Ludwig Institute for Cancer Research
Austin & Repatriation Medical Centre
Studley Road,
Heidelberg, Vic. 3084
Australia.

Tel 61-3-94965463
Fax 61-3-94965436
Email murphy_r@licre.ludwig.edu.au