Dataset Information

LC-MS/MS analysis of IαI proteoglycopeptides

ABSTRACT: The inter-alpha-trypsin inhibitor (IαI) complex is a macromolecular arrangement of structurally related heavy chain proteins covalently cross-linked to the chondroitin sulfate (CS) chain of the proteoglycan bikunin. The IαI complex is abundant in plasma and associated with inflammation, kidney diseases, cancer and diabetes. Bikunin is modified at Ser-10 by a single low-sulfated CS chain of 23-55 monosaccharides with 4-9 sulfate groups. The innermost four monosaccharides (GlcA3Gal3Gal4Xyl-O-) compose the linkage region, believed to be uniform with a 4-O-sulfation to the outer Gal. The cross-linkage region of the bikunin CS chain is located in the non-sulfated non-reducing end, (GalNAc4GlcA3)n ,to which heavy chains (H1-H3) may be bound in GalNAc to Asp ester linkages. In this study we employed a glycoproteomics protocol to enrich and analyze light and heavy chain linkage and cross-linkage region CS glycopeptides derived from the IαI complex of human plasma, urine and cerebrospinal fluid samples. The samples were trypsinized, enriched by strong anion exchange chromatography, partially depolymerized with chondroitinase ABC and analyzed by LC-MS/MS using higher-energy collisional dissociation (HCD). The analyses demonstrated that the CS linkage region of bikunin is highly heterogeneous. In addition to sulfation of the Gal residue, Xyl phosphorylation was observed although exclusively in urinary samples. We also identified novel Neu5Ac and Fuc modifications of the linkage region as well as the presence of mono- and disialylated core 1 O-linked glycans on Thr-17. Heavy chains H1 and H2 were identified cross-linked to GalNAc residues one or two GlcA residues apart and H1 was found linked to either the terminal or subterminal two GalNAc residues. The fragmentation behavior of CS glycopeptides under variable HCD conditions displays an energy dependency that may be used to obtain complementary structural details. Finally, we show that the analysis of sodium adducts provides confirmatory information about the positions of glycan substituents.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Urine, Blood Plasma, Cerebrospinal Fluid

SUBMITTER: Alejandro Gómez

LAB HEAD: Göran Larson

PROVIDER: PXD002707 | Pride | 2015-10-02

REPOSITORIES: Pride

ACCESS DATA

Dataset's files

Source:

			Action	DRS
	F016984_Urine_Betaelimination.mgf	Mgf
	F016984_Urine_Betaelimination.xml	Xml
	Fusion_150415_48_Urine_Betaelimination.raw	Raw
	QE_130604_05_CSF_0.4MNaCl.mgf	Mgf
	QE_130604_05_CSF_0.4MNaCl.raw	Raw

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Publications

Positive Mode LC-MS/MS Analysis of Chondroitin Sulfate Modified Glycopeptides Derived from Light and Heavy Chains of The Human Inter-α-Trypsin Inhibitor Complex.

Gomez Toledo Alejandro A Nilsson Jonas J Noborn Fredrik F Sihlbom Carina C Larson Göran G

Molecular & cellular proteomics : MCP 20150925 12

The inter-α-trypsin inhibitor complex is a macromolecular arrangement of structurally related heavy chain proteins covalently cross-linked to the chondroitin sulfate (CS) chain of the proteoglycan bikunin. The inter-α-trypsin inhibitor complex is abundant in plasma and associated with inflammation, kidney diseases, cancer and diabetes. Bikunin is modified at Ser-10 by a single low-sulfated CS chain of 23-55 monosaccharides with 4-9 sulfate groups. The innermost four monosaccharides (GlcAβ3Galβ3G ...[more]

PMID: 26407992

Similar Datasets

Project description:The inter-alpha-trypsin inhibitor (I?I) complex is a macromolecular arrangement of structurally related heavy chain proteins covalently cross-linked to the chondroitin sulfate (CS) chain of the proteoglycan bikunin. The I?I complex is abundant in plasma and associated with inflammation, kidney diseases, cancer and diabetes. Bikunin is modified at Ser-10 by a single low-sulfated CS chain of 23-55 monosaccharides with 4-9 sulfate groups. The innermost four monosaccharides (GlcA?3Gal?3Gal?4Xyl?-O-) compose the linkage region, believed to be uniform with a 4-O-sulfation to the outer Gal. The cross-linkage region of the bikunin CS chain is located in the non-sulfated non-reducing end, (GalNAc?4GlcA?3)n ,to which heavy chains (H1-H3) may be bound in GalNAc to Asp ester linkages. In this study we employed a glycoproteomics protocol to enrich and analyze light and heavy chain linkage and cross-linkage region CS glycopeptides derived from the I?I complex of human plasma, urine and cerebrospinal fluid samples. The samples were trypsinized, enriched by strong anion exchange chromatography, partially depolymerized with chondroitinase ABC and analyzed by LC-MS/MS using higher-energy collisional dissociation (HCD). The analyses demonstrated that the CS linkage region of bikunin is highly heterogeneous. In addition to sulfation of the Gal residue, Xyl phosphorylation was observed although exclusively in urinary samples. We also identified novel Neu5Ac and Fuc modifications of the linkage region as well as the presence of mono- and disialylated core 1 O-linked glycans on Thr-17. Heavy chains H1 and H2 were identified cross-linked to GalNAc residues one or two GlcA residues apart and H1 was found linked to either the terminal or subterminal two GalNAc residues. The fragmentation behavior of CS glycopeptides under variable HCD conditions displays an energy dependency that may be used to obtain complementary structural details. Finally, we show that the analysis of sodium adducts provides confirmatory information about the positions of glycan substituents.

Project description:Chondroitin sulfate proteoglycans (CSPGs), an important class of carbohydrate-modified proteins, are composed of chondroitin sulfate (CS) polysaccharide(s) attached to different core proteins. CS polysaccharides interact with a multitude of protein ligands to control key events in homeostasis and development. Much effort has been devoted to CS structural characterization, as the specificities of the interactions are considered to be determined by the distribution of sulfate groups along the polysaccharide chains. Owing to their structural complexity however, CS chains are typically characterized after they have been released from their core proteins, which precludes site-specific structural information. Such information would likely assist in assigning CSPG-related functions and provide insights to potential differences in CS structures for different core proteins and their glycosites. Here we utilize a novel glycoproteomic approach for the site-specific sequencing of CS modifications of CSPGs from human urine using a combination of biochemical enrichments, enzymatic digestions, and positive mode nano-scale liquid chromatography tandem mass spectrometry (nLC-MS/MS) analysis. Trypsin-derived CS-glycopeptides were partially depolymerized with chondroitinase ABC, yielding peptide-attached CS chains, ranging from 6 - 18 monosaccharides in length. Software-assisted- and manual analysis revealed that certain core proteins carried CS with abundant sulfate modifications, while others carried CS with lower levels of sulfation. Inspection of the amino acid sequences surrounding the attachment sites indicated that acidity of the attachment site motifs influenced the levels of CS sulfation and statistical analysis confirmed this relationship. These results demonstrate attachment site-specific CS polysaccharides of CSPGs in human urine and indicate that this novel method may assist in elucidating the biosynthesis and functional roles of CSPGs in cellular physiology.