I am trying to find out if there are any reasonable guestimates out there on the amount of protein in a total bacterial lysate from a certain amount of cells. All I could find so far is estimates about the number of protein molecules per cell, and number of cells per OD600. But has anyone ever quantified protein in total cell lysates?
I've always used NEB's estimates:
https://www.neb.com/tools-and-resources/usage-guidelines/protein-data
Do you want to know the concentration of total protein or an expressed protein? I anyway wouldn't try to estimate the protein concentration from the OD. There are to many parameter, which can alter the amount of protein, for example growth conditions, condition of your starter colony, age of medium and composition.
And even if it would work, it will be a really rough estimation..
Hi there,
The main problem is the OD unit as in fact what is measured with culture sample is not actually absorance but light scattering. Therefore readings will depends on spectrophotometer geometry( ie distance between sample and PM). To sum up, relationship between bacteria dry weight and OD will vary... But generally it is assumed that 1 OD at 600nm corresponds to 0.3g-0.5g dry weight per liter of wild type E. coli culture. And proteins are about 50% of dry weight so it would be 150 to 250µg of proteins per liter.
Thanks for the answers. I merely need a (rough) estimate to see how much culture i need to spin to have enough (total) protein for a MS determination (I need ca. 10-20mg for that). Based on Dominiques estimate, that would be be about 100mL of an OD600=1 culture. (I assume the ug is a typo, as before the dry weight is estimated at 0.3-0.5g/L).
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