BS04@primeb.dundee.ac.uk (04/02/91)
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@PRIMEB.DUNDEE.AC.UK Biological Sciences, Tel No: 0382-23181 Ext 4282 University of Dundee, Dundee Scotland DD1 4HN