Atomic Mass Unit (amu)
Atomic Mass Unit (amu) — A unit of mass equal to one-twelfth the mass of a carbon-12 atom, used interchangeably with Dalton in mass spectrometry of peptides.
What Is an Atomic Mass Unit?
The atomic mass unit (amu or Da, dalton) is the standard unit of molecular weight in peptide science. One dalton equals 1/12 the mass of a carbon-12 atom (1.66054 x 10⁻²⁴ g). Peptide masses are reported in daltons, and mass spectrometry measures mass-to-charge ratio (m/z) in dalton/charge units.
Context
- Average vs. monoisotopic: Average mass uses natural isotope abundances; monoisotopic uses the most abundant isotope of each element. Difference is ~0.05% for typical peptides
- Mass accuracy: Modern MS instruments achieve < 5 ppm accuracy (~0.005 Da for a 1000 Da peptide)
- Residue weights: Average residue weight ~111 Da. Quick MW estimate: 111 x number of residues
Frequently Asked Questions
What is Atomic Mass Unit (amu)?
A unit of mass equal to one-twelfth the mass of a carbon-12 atom, used interchangeably with Dalton in mass spectrometry of peptides.
Why is Atomic Mass Unit (amu) important in peptide research?
Atomic Mass Unit (amu) is a fundamental concept in unit 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
- Atomic Mass Unit (amu) on Wikipedia
- Search Atomic Mass Unit (amu) on PubChem (NIH)
- Research articles on ScienceDirect