Method and system for identifying Denovo by N-sugar chain structure based on mass spectrum data

Abstract

The invention belongs to the technical field of glycomics, and discloses an N-sugar chain structure identification Denovo method and system based on mass spectrometric data, and the method comprises the following steps: extracting structure and composition information of sugar chain fragment ions in the mass spectrometric data, and carrying out N-sugar chain identification based on a basic peak, a cross peak and a generalized monosaccharide dictionary, and reducing the search space of the identification result candidate structure by using a pruning strategy to obtain an N-sugar chain structure corresponding to the mass spectrum. On the basis of mass spectrum data of the N-sugar chain and the idea of Denovo, the structure and composition information of sugar chain fragment ions in the mass spectrum data is extracted, and the N-sugar chain structure corresponding to the mass spectrum is identified. In the identification process, basic peaks and cross peaks are introduced, and N-carbohydrate chain identification is carried out based on the basic peaks and the cross peaks; a generalized monosaccharide dictionary is introduced, the spectrogram quality is improved, and the robustness of the identification method to noise in mass spectrum data is improved; and reducing the search space of the identification result candidate structure by using a pruning strategy. According to the invention, the mass spectrum identification quality is improved.

Description

technical field [0001] The invention belongs to the technical field of glycomics, and in particular relates to a Denovo method and system for N-sugar chain structure identification based on mass spectrometry data. Background technique [0002] At present: Glycosylation of proteins is a post-translational modification of proteins ubiquitous in organisms, and its N-sugar chain structure determines the biological functions of glycoproteins to a large extent. With the rapid improvement of mass spectrometry technology, the use of mass spectrometry data to identify the structure of sugar chains has become an important way to understand the biological functions of glycoproteins. [0003] The N-glycan chain is a tree structure with a fixed structure of the pentasaccharide core. Currently, the identification methods of the N-glycan chain structure can be roughly divided into two categories: 1) database search method; 2) de novo sequencing (Denovo) method; 3) labeling. The labeling ...

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Problems solved by technology

[0010] The third type is a method based on dynamic programming: similar to de novo peptide sequencing, GLYCH uses dynamic programming technology to find the most likely branch structure from tandem MS mass spectra, which is only applicable to MS / MS spectra of released sugar chains and cannot be processed Glycopeptide data

[0013] (1) Current database search-based methods cannot identify unrecorded structures

[0014] (2) The current method based on de novo sequencing (Denovo) is greatly affected by the noise of mass spectrometry data, resulting in low robustness in identifying structures

Although the N-sugar chain has a tree structure, its composition and the position of each monosaccharide on the sugar chain may vary, which brings great challenges to accurately identify the sugar chain structure from mass spectrometry data;

[0018] (3) The stability of the N-sugar chain structure is different

The structural stability of different substructures is different, that is, some are not easy to break, and some are extremely fragile. However, the structural stability information of various substructures is unknown, which brings difficulties to the identification of N-glycan chain structures based on mass spectrometry data;

[0019] (4) The glycopeptides sent to the mass spectrometer may not be pure, which may actually be a mixture of various glycopeptides, which interferes with the identification of enriched glycopeptides;

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