How to show protein interaction?

Leemor Joshua-Tor leemor at CSHL.ORG
Fri Nov 29 10:26:23 EST 1996

Achim Recktenwald wrote:

>Cornelius Krasel wrote:
>> Thorsten Schmidt (Thorsten.Schmidt at wrote:
>> > I have a protein and I just want to test if it forms dimers, trimers etc.?
>> > (The protein was purified by HisTag-Chromatographie and is in solution
>> > (20mM Tris, 0,5 M NaCl, 1 M Imidazol))
>> > What is the simplest way to do this?
>> I'd try analytical gel filtration if you have the equipment (i.e. an
>> FPLC/HPLC). Alternatively, you may try analytical ultracentrifugation
>> (I have absolutely no experience with this) or maybe non-denaturing
>> gel electrophoresis.
>> --Cornelius.
>> --
>> /* Cornelius Krasel, U Wuerzburg, Dept. of Pharmacology, Versbacher Str. 9 */
>> /* D-97078 Wuerzburg, Germany   email: phak004 at  SP3 */
>> /* "Science is the game we play with God to find out what His rules are."  */
>I would also try native polyacrylamide-gel-electrophoresis. If the bond
>between the subunits is strong, you'll get one single band, the multimer
>form; if its very weak, you'll only see a sharp band at the mol. weight
>for the single subunit. But if the bond is neither nor than you get a
>smear on your gel, starting at the point of the highest multimer down to
>the lowest multimer, or even the single subunit. In the latter case the
>multimer form is constantly decomposing during the electrophoresis.

Analytical ultracentrifugation is the most precise and direct way to
determine molecular weight and thus oligomeric form, if you can get
access to one. The second choice would be a light scattering experiment
where you are determining the radius of the particle. Both of these
require access to the proper insturmentation. Gel filtration and native
gel-electrophoresis should be always taken with a grain of salt since
they often give misleading results because they are a very indirect
way of getting at the MW of the particles.


  Leemor Joshua-Tor, Ph.D.
  Assistant Investigator
  Cold Spring Harbor Laboratory           Tel. (516) 367 8821
  1 Bungtown Road                         Fax  (516) 367 8873
  Cold Spring Harbor, NY 11724            e-mail: leemor at

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