Deep Coverage and Extended Sequence Reads Obtained with a Single Archaeal Protease Expedite de novo Protein Sequencing by Mass Spectrometry

ABSTRACT: Label-free protein sequencing is critically enabled by bottom-up, mass spectrometry-based proteomics workflows. Applications such as antibody sequencing or antigen discovery require de novo reconstruction of peptide and protein sequences. While trypsin has long served as the gold-standard protease in proteomics, its restricted C-terminal cleavage specificity constrains peptide diversity, particularly limiting coverage in antibody hypervariable complementarity-determining regions (CDRs). As a result, current workflows yield sparse reads and sequence gaps. Although multi-protease and hybrid-fragmentation strategies can notably improve coverage, they add complexity and compromise scalability and reproducibility. Here, we present a novel approach using HyperThermoacidic Archaeal (HTA) proteases Krakatoa or Vesuvius as powerful single-enzyme solutions for de novo antibody sequencing. Each protease generated over five times more unique peptide reads than trypsin or chymotrypsin with high redundancy across CDRs. Combined with EAciD fragmentation on a ZenoTOF 7600 system, this workflow enabled complete, unambiguous antibody sequencing. Despite most de novo tools being optimized for CID/HCD-tryptic data, analysis using PEAKS/DeepNovo and Stitch softwares showed that HTA-Proteases yielded up to fourfold higher alignment scores and fewer sequence mistakes across variable regions. Redundant reads increased more than threefold compared to standard proteases, boosting confidence in amino acid assignment and reducing ambiguity in final assemblies. Our alternative HTA-EAciD approach offers short digestion times, eliminates extensive cleanup, and enables analysis in a single LC-MS/MS run. This single-protease strategy delivers sequencing performance comparable to multi-enzyme workflows, providing a scalable, efficient, and highly confident approach for de novo sequencing in antibody discovery and beyond.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Tereza Kadavá  

LAB HEAD: Albert JR Heck

PROVIDER: PXD063988 | Pride | 2026-03-17

REPOSITORIES: Pride