amino acid weight confusion

Question

[jsbrava]

I'm taking a class that uses stepic.org. We're given a list of amino acid weights:

https://stepic.org/lesson/CS-Generating-the-Theoretical-Spectrum-of-a-Peptide-4912/step/1

For example, it gives the weight of A as 71 Daltons

Biopython gives a weight of 89 (units ?)

http://biopython.org/DIST/docs/api/Bio.Data.IUPACData-module.html#monoisotopic_protein_weights

In what units are the Biopython weights? Can I get Daltons?

Thanks,
Jim

Answer 1

[russhh]

water has a molecular mass of 18 and a water molecule is lost for every peptide bond that is formed during protein synthesis

[jsbrava]

OK, for my purposes I need to subtract the 18 for water.

Thanks!