Skip to content
Login Register

#peptide m/z

2 public questions tagged with this topic.

Mass Spectroscopy

A peptide with m/z values 301, 401, 501, 601 suggests MWs of:

The observed m/z values can originate from different neutral masses carrying different charges according to deconvolution formula M = z*(m/z) - z*proton mass. For pure species, peaks 301 and 401 both correspond to mass near 1200 Da when charges are four and three respectively: 301×4-4=1200 and 401×3-3=1200. Similarly, peaks 501 and 601 can be reconciled with mass around 1500 Da under appropriate charge assumptions, indicating coexistence of two proteins. This pattern demonstrates how a single ESI spectrum may contain interleaved charge series revealing molecular weights of 1200 and 1500 Da from mixture analysis.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

View Details
Mass Spectroscopy

In ESI-MS, a peptide of 1500 Da with +3 charge shows m/z of:

Electrospray mass spectrometry detects multiply charged ions where measured m/z equals neutral mass plus charge-carrying protons divided by number of charges. Mathematically, m/z = (M + z*1.0073)/z. For a peptide weighing 1500 Da with three added protons, total mass becomes approximately 1503 Da, divided by three charges yields about 501 m/z. This charge reduction principle enables detection of large peptides within limited analyzer range. Understanding this calculation is essential for manual deconvolution and interpreting charge-state envelopes observed in protein ESI spectra during proteomic experiments.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

View Details