Missed Cleavages in Peptide Mapping: Better Digestion Has a Coverage Tradeoff

Peptide mapping depends on reproducible proteolysis. A missed cleavage can spread a modification signal across several peptide forms, complicating relative quantification and comparison between runs. Yet the longest possible digestion is not automatically best: it can increase preparation-induced modifications, and a more complete cut may remove a longer peptide that formerly covered a hard-to-see sequence region.

A measured comparison

Kristensen and colleagues compared three trypsin digestion workflows for monoclonal-antibody multi-attribute LC–MS analysis: an optimized two-step automated protocol, an original one-step automated protocol and a conventional method. The study included eight antibody samples across reference and internal projects. The two-step protocol used 15 minutes at 75 °C followed by 30 minutes at 40 °C under the authors’ specified buffer and enzyme conditions. [1, Experimental Section]

Across their peptide-identification comparison, the average share of identified peptides with zero missed cleavages was 60% for the two-step protocol, versus 32% for the one-step and 34% for the conventional protocol. These are shares among identified peptides in the study’s datasets, not the percentage of antibody molecules completely digested. The paper also reports slightly lower MS/MS sequence coverage for the two-step workflow; the authors attributed that to loss of longer missed-cleavage peptides and cautioned that critical regions require inspection. [1, Results, Figures 3–4 and Table S5]

What to examine in an actual peptide map

First specify the cleavage rule and count missed-cleavage forms by sequence, not just in aggregate. Compare extracted-ion chromatograms for the fully cleaved and longer forms of a critical peptide, including modification states. Inspect sequence coverage of functional or quality-relevant regions; a global improvement can hide a local gap. Review digestion time, temperature, pH, reduction, enzyme activity and quench timing as a linked procedure. If the method will be used for trending, set acceptance criteria on relevant peptide forms and demonstrate repeatability across days and analysts.

The same paper separately tested C4 and C18 reversed-phase columns for hydrophobic peptides. In one USP mAb3 comparison, carryover in the next blank for peptide H44–65 was 0.21% on Accucore C4 versus 12.06% on Accucore C18. This result illustrates that a difficult map may contain both a digestion problem and a chromatography problem. It does not mean every C4 column will outperform every C18 column: the paper’s Hypersil comparison differed, and sequence coverage must still be checked. [1, Table 1]

An independent NISTmAb peptide-mapping optimization compared trypsin sources and evaluated missed cleavage, nonspecific cleavage, autolysis and total identified-peptide intensity together. The recombinant porcine candidate had three percentage points fewer missed cleavages than the two remaining sources in that experiment, but the authors did not find a single overwhelming winner across all criteria. That reinforces the central decision: avoid choosing a digestion condition on one global percentage alone. [2, Figure 6]

Minimum map comparison record

Use the same input material and LC–MS sequence when comparing digests. Archive the cleavage-form distribution by peptide, total sequence coverage, coverage of critical regions, modification fractions, autolysis/background peaks and blank carryover. If a zero-missed-cleavage share improves but a required region disappears, the new procedure needs more work before adoption.

Evidence limit and next step

These results come from tryptic maps of antibodies, not from an undigested catalog peptide and not from a NHD lot. Use the study to design a local comparison, then verify identity with the LC–MS peptide guide and document the map’s sequence coverage and modification assignments. A clean peak count alone is not complete structural evidence.

Primary source and claim trail

1. Kristensen DB, et al. Optimized Multi-Attribute Method Workflow Addressing Missed Cleavages and Chromatographic Tailing/Carry-Over of Hydrophobic Peptides. Analytical Chemistry. 2022;94:17195–17204. DOI 10.1021/acs.analchem.2c03820, PMID 36346901. Locations: Experimental Section → “Optimized Two-Step SMART Digestion Protocol” (time/temperature); Results → “Optimized Two-Step SMART Digest Protocol,” Figures 3–4 and Table S5 (60/32/34% and coverage caveat); Table 1 (C4/C18 H44–65 carryover). Primary full text inspected.
2. Mouchahoir T, Schiel JE. Development of an LC-MS/MS peptide mapping protocol for the NISTmAb. Analytical and Bioanalytical Chemistry. 2018. Location: Results, Figure 6 and its discussion (trypsin-source comparison and three-percentage-point missed-cleavage difference). Independent primary method study; not pooled with [1].

Editorial source check: Codex AI-assisted editorial review · 2026-09-23T19:26:53+08:00