Technical Information Useful for Protein Purification

E. coli Protein Yield Information
Bacterial Cells: Escherichia coli or Salmonella typhimurium
Cell Data per cell per liter at 109 cells per ml
Wet Weight 9.5 x 10–13 g 0.95 g
Dry Weight 2.8 x 10–13 g 0.28 g
Total Protein 1.55 x 10–13 g 0.15 g
Volume 1.15 µm3 = 1 femtoliter  
Protein conc. in the cell: 135 mg/ml

Theoretical maximum yield for a protein
of interest from 1 liter of culture (109 cells/ml):

0.1% of total protein: 150 µg/liter
2.0% of total protein: 3 mg/liter
50.0% of total protein: 75 mg/liter


Useful Protein Websites

SwissProt

www.expasy.org
Protein Data Bank www.rcsb.org/pdb
Enzyme Database www.brenda-enzymes.info
Human Mitochondrial Proteins bioinfo.nist.gov
NCBI Structure Site www.ncbi.nlm.nih.gov/Structure
 
Acrylamide Gel Resolution of Proteins
Recommended
% Acrylamide
Protein Size Range
8% 40 - 200 kDa
10% 21 - 100 kDa
12% 10 - 70 kDa

Protein Molar Conversions
100 pmoles of 100,000 dalton protein = 10 µg
100 pmoles of 50,000 dalton protein = 5 µg
100 pmoles of 10,000 dalton protein = 1 µg

Protein Molar Conversions (Formula)
µg protein = Protein size(kDa) x pmole protein x
109 µg/g x mole/1012 pmol

Protein/DNA Conversions
1 kb of DNA = 333 amino acids = 3.7 x 104 dalton protein

10,000 dalton protein = 270 bp DNA
50,000 dalton protein = 1.35 kb DNA
100,000 dalton protein = 2.7 kb DNA