For laboratory research use only. Not for human consumption. Not for clinical or therapeutic use. Not evaluated by the FDA.
For laboratory research use only. Not for human consumption. Not for clinical or therapeutic use. Not evaluated by the FDA.
Molecular weight is the mass of a peptide molecule, confirmed by mass spectrometry. The observed mass should match the theoretical mass within a narrow margin to verify sequence identity.
Molecular weight is expressed in daltons (Da) and may be reported either as the monoisotopic mass, using the most abundant isotope of each element, or the average mass, weighted across natural isotope abundances. The theoretical value is calculated by summing the constituent residue masses and subtracting one water molecule for every peptide bond formed.
Mass spectrometry supplies the observed value; in electrospray ionization a peptide often appears in several multiply-charged states that are deconvoluted back to a single mass. Agreement between the observed and theoretical weight within a narrow tolerance confirms identity, whereas a discrepancy flags a wrong, truncated, or unexpectedly modified sequence.