[RASMB] Metrizamide or Nycodenz as density contrast agent

[Brown, Patrick (NIH/NIBIB) [E]]

Dear RASMB’ers:

Ariel Lustig has asked me to post his response here to an email I had sent him soliciting his experience with metrizamide and nycodenz as density contrast agents:

“Most runs are
 done  with Nycodenz, since  as you can  see  on the attached  graph ,  their  viscosity is relative
lower and easier to work  with. All  the  attach. scanned  from   the  shown  booklet, may be the  address
has changed. To dissolve in   buffer such high  concentration of  Nic.is  hard. I have done it in a  volumetric
 flask of about  100 mL added  slowly   the  powder  and then the  buffer at  about  40°C , shake it antil
the next  day the  solution  become  clear! Only then   I measured the  density in  a density  meter at 20°C
with as little as possible  air-bubles.(it is  hopeless  to take out the  air  from the solution =stock solution. Only  later I delute the  st-solution wis my membrane protei  solution. (it is  somewhere  discribed in the BBA paper)
My luck was that all my paper is about hydrated micelles so  I never  needed to rise the   density over ro =1.2g/mL.
I added  a paper  of  Ruf et al , The used also my priciple lttle  different
I added also the way /prograsm  how I  calculate Segal program.”


The literature to which Ariel refers is:
Machaidze, G. & Lustig, A. Journal of Biological Physics and Chemistry (2006) 6, 91-102.
Ruf, A. et al. Biochemical and Biophysical Research Communications (2004) 315, 247- 254.
Lustig et al. Biochimica et Biophysica Acta (2000) 1464, 199-206.


Hope this is helpful to someone out there…

Patrick
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