[Biojava-dev] Calculation error in MassCalc.getMass()

[Matthew Pocock]

Hi Jerry,

I don't know anything about masses. Could someone else from the list 
seccond this? We should get this sort of thing right.

Matthew

Jerry Thomas wrote:
> I believe the masses returned by MassCalc.getMass() to be incorrect.
> 
> The internal residue masses used for amino acids are correct, but the 
> terminii are calculated incorrectly.  Instead of adding H for the 
> N-terminus and OH for the C-terminus, the masses of two OHs are added. 
> For M+H, instead of adding an extra H, the mass of a third hydroxyl is 
> added!
> 
> For example, MassCalc gives a monoisotopic M+H mass for angiotensin 
> (DRVYIHPFHL) of 1328.6751, whereas the correct value is 1296.6853.  The 
> difference is due to the two extra oxygens (2 * 15.9949 = 31.9898).
> 
> If there are no objections, I will correct the code, and add a test app 
> to demos.
> 
> cheers,
> 
> Jerry
> 
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