Dear researchers,
My research is to determine which peptides pose antiviral activity.
I used Acrylamide: Bis-Acrylamide Ratio 13:1 as this is ideal for Peptide separation and Color Marker Ultra-low Range (M.W. 1,060-26,600).
After doing SDS-PAGE, I have to cut the bands out and do gel trypsinization before I sent the bands to LC-MS.
From the SDS-PAGE gel (before I cut the bands out),
May I know how to determine which bands are peptides?
What is the molecular weight of the peptides (kDa)?
have to know which specific bands I should cut, and not simply just cut all the bands out......
I can only run LC-MS if I able to find out which bands are peptides. It is impossible to cut all the bands out. So, I have to determine which bands are peptides.
From what I know,
Peptide is smaller than protein.
May I know should I cut the bands which locate at the below part of the gel?
May I know I should cut from which range?
(The lower the position of the bands, the lower the molecular weight of proteins) as smaller proteins move faster.
Thank you!
If they stain with Coomassie Brilliant Blue, they are peptides. With regard to their molecular weights, you can run a protein ladder alongside which will tell you the MWs of the different bands.
There is no real distinction between peptides and proteins, other than molecular weight. Both are linear chains of amino acids. Very short chains are referred to as peptides and long ones as proteins.
Hello, as smaller molecular weight of peptide as higher will be position in gel.
Use ESI-MS or MALDI-MS for farther analysis of peptides and more exact detection of molecular weight.
As Dr. Shapiro pointed out, the difference is essentially in the molecular weight or chain's size. According to Britannica, peptides are "defined as molecules that consist of between 2 to 50 amino acids, and proteins are made up of 50 or more". Lehninger's Principles of Biochemistry, on the other hand, states that "polypeptide signifies polymers of generally less than 10,000 mw, whereas the term protein refers to longer polymers."
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