The molecular weight of a protein is calculated by adding up the molecular weights of the amino acids, per standard calculations.
In Benchling, the following molecular weights are assigned to amino acids:
- A: 89.09
- B: 132.65
- C: 121.15
- D: 133.1
- E: 147.13
- F: 165.19
- G: 75.07
- H: 155.16
- I: 131.17
- J: 131.2
- K: 146.19
- L: 131.17
- M: 149.21
- N: 132.12
- O: 255.31
- P: 115.13
- Q: 146.15
- R: 174.2
- S: 105.09
- T: 119.12
- U: 168.06
- V: 117.15
- W: 204.23
- X: 143.7
- Y: 181.19
- Z: 146.75
Notes
We have lightly modified constants from biopython, to match results from expasy. These are the average isotopic masses, as opposed to the monoisotopic mass. See http://www.ionsource.com/tutorial/isotopes/slide8.htm.
Molecular weights for B and Z are non-standard and were reverse engineered from
http://web.expasy.org/protparam/.
Molecular weights for J and X were taken from Geneious.