note on units.... and a couple of questions......

BS04 at primeb.dundee.ac.uk BS04 at primeb.dundee.ac.uk
Tue Apr 2 07:29:00 EST 1991


A couple of things..... on one of the quietest lists I am on.

 I just got a mail shot checking the use if my units in the note I
wrote about Proteases.... mol/m3. This is ment to represent:

    moles in 1 cubic metre.... and is the same as mM in Old_Speak..

 sorry if this caused any confusion.  But it is the S.I. units I routinely use.


 The second point is a question about FPLC ion-exchange profiles. I am
using a Millipore MemSep 1000 anion exchange column on a Pharmacia FPLC
control system. It works well but I have recently noticed that my major
protein/enzyme activities do not relate to the OD 280 chart recorder
profile. I have taken into account the lag between the monitor and the
fraction collector but there still seems to be a fudge factor missing.
the protein I am working on is RUBISCO, the major plant protein in size
and amount... so it should not be a matter of the OD 280 peak being
a minor one and the specific activity very high.


  A third, and last, question. Once fractions have been bulked after ion
exchange, and the average salt conc is 100 mol/m3 (100 mM NaCl), is desalting
needed before concentrating with (NH4)2SO4....... ?


Many thanks for reading this far....


Andy Johnston.



Andrew M. Johnston,                    E-Mail: BS04 at PRIMEB.DUNDEE.AC.UK
Biological Sciences,                   Tel No: 0382-23181 Ext 4282
University of Dundee,
Dundee
Scotland
DD1 4HN





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