About how many typical amino acids are found in proteins?
1 Answer
Varies enormously.
Explanation:
There is no hard and fast lower boundary for the number of amino acids that can compose a so-called protein molecule. Most biochemists would assume that a 'protein' has enough amino acids in it to have assume a relatively stable conformation.
A small cytokine (i.e., protein signaling molecule) might have 40 amino acids in it. Amino acid chains too small to be considered a proper protein are often called polypeptides.
Similarly, there is no hard and fast boundary on the upper end of protein size. Again, you run into classification issues - do you consider 'a protein' to be simply folded out of one continguous chain of covalently bonded amino acids, or do you expand that definition to include an assembly of several non-covalently bounded chains of amino acids?
Your typical, garden variety mid-sized kinase (i.e., a standard globular protein) has around 1200 residues.
