Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.52 (PNGase F)
 1,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Characterization of the major human milk fat globular membrane proteins was carried out using proteomic techniques comprising two-dimensional polyacrylamide gel electrophoresis, followed by in situ PNGase F and trypsin digestion. Matrix-assisted laser desorption/ionization quadrupole time-of-flight and electrospray ionization mass spectrometry identified seven major protein components: alpha-lactalbumin, lysozyme precursor, beta-casein, clusterin, lactotransferrin, polymeric immunoglobulin receptor precursor, and human milk fat globule EGF-factor 8 protein. Sequence information on the protein-associated glycans was determined by matrix-assisted laser desorption-ionization quadrupole time-of-flight hybrid mass spectrometry. This glycan analysis revealed interesting fucosylation branching patterns which may be influential in maternal protection of the newborn against bacterial and viral pathogenic attack.
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PMID:Use of proteomic methodology for the characterization of human milk fat globular membrane proteins. 1181 2

Clusterin is suggested to be involved in the pathogenesis of Alzheimer's disease. Clusterin expression is increased in brain tissue in affected regions of Alzheimer patients, and intense clusterin staining is found in both senile plaques and in neuronal and glia cells. In contrast, the cerebrospinal fluid level of clusterin in Alzheimer patients has, thus far, been found unchanged. Clusterin is a glycosylated protein, and an alteration of its glycosylation in Alzheimer's disease might influence accurate quantification in cerebrospinal fluid through interference of antibody binding to the protein. Using enzymatic deglycosylation of clusterin isolated from cerebrospinal fluid, we found that the carbohydrates attached to clusterin were of the N-linked type and sialic acids. Based on this finding, cerebrospinal fluid samples from Alzheimer patients (n=99) and controls (n=39) were analysed. The samples were treated with peptide: N-glycanase F, cleaving off N-linked carbohydrates, and clusterin was quantified before and after deglycosylation using a new sandwich enzyme-linked immunosorbent assay. Clusterin was significantly increased in Alzheimer patients, in both native (7.17+/-2.43 AU versus 5.73+/-2.09 AU; p=0.002), and deglycosylated samples (12.19+/-5.00 AU versus 9.68+/-4.38 AU; p=0.004). Deglycosylation led to increased measured levels of clusterin by 70% (p<0.001) in Alzheimer patients and 67% (p<0.001) in controls. These findings indicate that glycosylation of proteins may interfere with their quantification. The results show that clusterin is significantly increased in cerebrospinal fluid from Alzheimer patients as a group, supporting that clusterin might be involved in the pathogenesis of Alzheimer's disease. However, the individual clusterin levels overlap between the two groups, and thus cerebrospinal fluid clusterin measurement is not suitable as a biochemical marker in the diagnosis of Alzheimer's disease.
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PMID:Clusterin in cerebrospinal fluid: analysis of carbohydrates and quantification of native and glycosylated forms. 1649 Feb 86

Chicken egg white (CEW) is a perfect source of natural proteins that possesses outstanding functional properties and various bioactivities. The glycosylation structure of CEW proteins plays important roles in their functions, bioactivities, and allergies. The present work attempted to identify N-glycosites of CEW proteins using an omics strategy. CEW proteins were digested with trypsin and chymotrypsin; glycopeptides were enriched and deglycosylated using PNGase F in H218O water, followed by analysis using high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS). A total of 71 N-glycosites in 26 CEW glycoproteins were identified. Web-Logo analysis showed that most of the N-glycosites were at N-X-T (55%) and N-X-S (32%). Furthermore, two-dimensional electrophoresis of CEW clusterin demonstrated a series of spots horizontally distributed at 35-37 kDa with an extremely wide isoelectric point range of 4.54-6.68, indicating the heterogeneity of glycosylation of CEW clusterin. These results provided important information for the understanding of the structures, functions, and bioactivities of CEW glycoproteins.
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PMID:Identification of N-Glycosites in Chicken Egg White Proteins Using an Omics Strategy. 2858 47