Monoisotopic Mass
Monoisotopic Mass — The exact mass of a peptide calculated using the most abundant isotope of each element, used for precise identification in mass spectrometry.
What Is Monoisotopic Mass?
Monoisotopic mass is the molecular mass calculated using the most abundant isotope of each element (¹²C, ¹H, ¹⁴N, ¹⁶O, ³²S). For peptides < 2,000 Da, the monoisotopic peak is the most abundant isotope peak in the mass spectrum. Above ~2,000 Da, the average mass becomes more prominent.
Monoisotopic vs. Average
- Monoisotopic: Most precise. Used for peptide identification and de novo sequencing. Always lighter than average
- Average: Weighted average of all isotopes. Used for large proteins. Reported on CoA
- Mass accuracy: Modern instruments achieve < 5 ppm mass accuracy on monoisotopic peaks
Frequently Asked Questions
What is Monoisotopic Mass?
The exact mass of a peptide calculated using the most abundant isotope of each element, used for precise identification in mass spectrometry.
Why is Monoisotopic Mass important in peptide research?
Monoisotopic Mass is a fundamental concept in analytical as it relates to peptide science. It directly influences experimental design, compound characterization, and the reliability of research outcomes across biochemistry and molecular biology disciplines.
Authority Sources
- Monoisotopic Mass on Wikipedia
- Search Monoisotopic Mass on PubChem (NIH)
- Research articles on ScienceDirect