Mass spectrum-based complex cross-linked peptide fragment identification method

Abstract

The invention relates to a mass spectrum-based complex cross-linked peptide fragment identification method, and belongs to the technical field of biological analysis. The method comprises the following steps: firstly, carrying out theoretical enzyme digestion on proteins in a protein library and establishing a peptide fragment index; then assuming a cross-linking site on each peptide fragment and establishing an ion index; performing ion complementation hypothesis on the spectrogram, performing peptide spectrum matching by using an ion index, and finally performing coarse scoring, fine scoring and re-scoring to obtain a final result. According to the method, peptide spectrum matching can be directly carried out on the spectrogram and all cross-linked peptide fragments meeting the conditions, the peptide fragments with the correct result of the spectrogram are basically distributed in the top ranking position, and the correct result can be recalled simply by carrying out fine scoring once again in a very small retrieval space.

Description

Technical field [0001] The present invention relates to a method of identifying a complicated crosslinked peptide segment based on mass spectrometry, belonging to the field of biological analysis. Background technique [0002] Crosslinked proteomics aims to clarify the structural characteristics of protein network in cells, understand the life mechanism from the molecular level, and finally used for the design of the drug. Crosslinking mass spectrometry has high throughput, high sensitivity, etc., which can achieve large-scale protein crosslinks in complex samples. Among them, the identification of the crosslinking peptide segment is the key to acquiring protein crosslinking information. Crosslinked peptides include three basic forms: MONO-LINK, LOOP-LINK and CROSS-LINK, also known as simple crosslinking forms. However, in the actual process, it is affected by the uneven distribution of the enzyme cut site and the crosslinking site, there may be a plurality of crosslinked peptide...

AI Technical Summary

Problems solved by technology

At present, many methods are available for the identification of simple cross-linked peptides in mass spectrometry data, but there is little research on the identification of complex cross-linked peptides

Because there are multiple cross-links in complex cross-linked peptides, the fragmentation rules and fragment ions are not exactly the same as those of simple cross-linked peptides, so the identification method of simple cross-linked peptides cannot be used for the identification of complex cross-linked peptides. Identification

Due to the introduction of multiple cross-links, even if the peptide bonds between the cross-link sites in the peptide are broken, there is no difference in the mass of the fragment ions obtained, and they do not help in the peptide spectrum matching process.

These fragment ions, if normally generated and used for peptide spectrum matching, will lead to erroneous identification results.

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