Converting micrograms to moles for IgG

Mike Clark mrc7 at cam.ac.uk
Mon Nov 13 05:15:14 EST 2000


In article <8uobvk$d2j$1 at oyez.ccc.nottingham.ac.uk>, Student
<URL:mailto:mucineer at iname.com> wrote:
> This may sound a very silly question to many of you. Whilst I know how to
> convert mass to moles for small molecules, I have never done it for large
> proteins. For an IgG1 molecule, I know the size is approximately 150kDa.
> Does this mean that 1 mole = 150,000grams? (It would be rather tedious to
> add up all the molecular weights of the amino acids to get the molar mass!)
> 
> Thanks, and excuse my ignorance!
> 
> 

150,000 Mr is a good working round figure approximation for an IgG
molecule. 

As a useful rule of thumb I generally estimate as follows

a single Ig domain = 12,500 Mr 
there are two of these in a light chain = 25,000 Mr  
and four in a heavy chain = 50,000 Mr 

An IgG has two heavy and two light = (2x25,000)+(2x50,000) = 150,000

Mike                              <URL:http://www.path.cam.ac.uk/~mrc7/>
-- 
 o/ \\    //            ||  ,_ o   M.R. Clark, PhD. Division of Immunology
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