Re: Iodination of peptides

Richard Laursen (laursen@bu.edu)
Tue, 13 Oct 1998 19:11:57 -0500

It is certainly possible that you got a tetraiiodo derivative, since both
tyrosine and histidine can be diiodinated [Means and Feeney, "Chemical
Modification of Proteins," pp. 175-182; Covelli and Wolff, J. Biol. Chem.
241, 4444 (1966)]. Since you are using cold iodine, you may be using a
much higher concentration than one would use for radio-iodination.
Apparently diiodination of tyrosine is favored under neutral or slightly
acidic conditions. Iodination of histidine is only slightly slower than
for tyrosine, according to the above references.

Richard Laursen
-------------------------------

>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

Richard A. Laursen
Department of Chemistry
Boston University
590 Commonwealth Ave.
Boston, MA 02215
Tel (617) 353-2491; FAX (617) 353-6466
email: <laursen@bu.edu>