## spectrum, parent monoisotopic mass error minus## SyntaxThe value is a positive floating point number (T ## Notes- Interpretation of this value depends on the value set for spectrum, parent monoisotopic mass error units.
- TANDEM inserts a default value for this parameter if it doesn't exist or is set to 0.0.
## DescriptionTANDEM uses this value as part of the calculation to determine if a particular peptide
sequence is to be considered as a possible model for a spectrum. The calculated mass of
the peptide is compared with the value using the following expression, where m d = m If the conditions d < 0 and T This condition (as well as the "plus" condition) are used to limit the extent of the more elaborate fragment by fragment calculations that are performed to truly match a peptide with a spectrum. From a mathematical point of view, if these conditions are not met, the peptide sequence is assigned a score of -∞ and discarded. Most protein identification tools use a single parameter for this type of matching, requiring
a symmetric condition T see also: spectrum, parent monoisotopic mass error plus | spectrum, parent monoisotopic mass error units X! TANDEM API description project |