[RASMB] membrane protein

[Ariel Lustig]

Dear colleauges,
Mainly for  those who are  interested in membrane proteins.
 For the  determination of  of  the  molecular  masses of  membrane  proteins (MP) are used different methodes,
some are complicated  to  run  or /and to calculate  the the  protein-only  of the detergent complex.  Since  long time  
I deal with this  probleme and in the  year  2000 we published  in BBA N°1464  page199-206
>>Molecular weight determination of  MP by SE at sucrose  or  Nycodenz-adjusted density of hydated  det.micelle.<<
 by  Ariel Lustig, Andreas Engel, Georgios  Tsiotis, Ehud M Landau ,Werner Baschong
Some other groups who tried different methodes criticized (partly) and it is  their   right . This practical proceedure
that is described in detail does not  obey the  the chapter "Detergent-solubilized  Protein" of the Beckman booklet of 
Greg Ralstone ! even  so...we can live  with it.
As shortly appeared  the 5th publication using this methode in quite  good papers,  the methode  seems not to be 
the  worst and is applicable. I like to  give  you  the  list:
 The J. of  Biological Chemestry  vol  276  N° 33  Aug.2001 p.30845
>>Sarcolipin , the  shorter Homolouge of  Phospholamban...<<..by  Simon Hellstern, Stefano Pegorarog, C B  Karim,   A Lustig, D Thomas  L moroder. Juergen  Engel. In this  paper  even  2 detergents  were emploid and  concentration dependence could  be  recorded

 The  Hoffman La Roche Pharma  Research published in   (BBRC) Bioche. and  Bioph. Research Commun.315
2004  p247 >> the monotopic membrane  protein human oxidosqualene cyclase....>>
by Armin  Ruf, Francis  Mueller ,B Arcy ...and  ..R Thoma

In several different detergents the protein run  by  SE and it is  easy to see  who  are  the  best and in which  concentration and  density worth  to  use. The  OG was matched  with  sucrose and hydration  corrected.
Interesting to learn how  some   MP  " feel  well"  in a certain  Detergent and other  not as shown   With   
MAO B or  MAO A Here the  best  Chois was ZW Zwittergent 3-12   ro =10449 and made  gravitational transparent  
with  buffer^/D2O 
PNAS vol 102  N° 36  sept 2005 p12684...
>> Three -dimensional structure of  human  monoamine  oxidase  A  MAO A ...MAO B
Luigi de Colibus, Min Li ,  Cl. Binda, A Lustig,  D. Edmondson  A. Mattevi

The  Aquaporin  not as  several Porins who forms  a three-mer channel could recently be  determined  in
J Mol Biol Communication  November 2005 is tetrameric.
>>Co-axial association of  Recombinant EYE  LENS Aquaporin.....<<
 D. v. Palanivelu , D  Kozno, And. Engel. K. suda, a. Lustig P.Agre, T.Schirmer.

The contribution  of the  anal. ultracentrifugation is mainy to show the behavior  of Mem-protein  in  solution,
since in SDS they run wrong so also in sefadex or similar cloumns. In EM detergent obscurs etc..
L-Scatteringgive only  averages.
The  sucrose for matching  the detergent  micelles causes to strong  hydration of the detergent-micell. Incase  of 
DM from ro 1.22 to 1.12.
and the  protein (as longtime  was known with high molar salt  that the shift  may be  from ro 1.35 to 1.28  about) so the  hydration as we corrected it is not so precise but helps for  the  contribution of the shown papers.
yours ,,,,   ariel
 
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