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

The major cathepsin B-like proteinase of adult Schistosoma japonicum has been isolated for the first time. Affinity chromatography with the mammalian cathepsin B inhibitor glycyl-phenylalanyl-glycine-semicarbazone purified a protein that was identified by N-terminal sequencing as Sj31. Sensitivity of Sj31 to PNGase F demonstrated the presence of asparagine-linked N-glycan. Marked resistance to the action of Endo-beta-glycosidase H indicated that most of the N-glycan chains are of the complex type. Binding of horseradish peroxidase-conjugated lectins demonstrated the presence of N-mannose, N-acetylglucosamine, and N-acetyllactosamine type 2 in the N-glycan. Fucose was not detected, and the presence of sialic acid remained questionable. Sj31 degraded the fluorogenic substrates Z-Phe-Arg-NMec and Z-Arg-Arg-NMec with an optimum between pH 5.0 and 6.0. The specific activity was 18-21-fold higher with the Phe-Arg substrate compared with the Arg-Arg substrate, whereas this value was 4-6-fold for bovine spleen cathepsin B, thus suggesting differences in the S2 subsite between parasite and host proteinases. Quantitative purification of Sj31 led to the conclusion that cathepsin B-like activity predominates over cathepsin L-like activity in S. japonicum. Because Sj31 degraded hemoglobin in vitro and was localized in the parasite gut, the proteinase may degrade ingested proteins in vivo.
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PMID:Affinity isolation and characterization of the cathepsin B-like proteinase Sj31 from Schistosoma japonicum. 940 88

We have studied the structures of asparagine-linked oligosaccharides of cathepsin L purified from rat liver in detail. The oligosaccharides released from rat liver cathepsin L on glycopeptidase-F treatment were tagged with 2-aminopyridine at their reducing ends. The pyridylamino (PA) derivatives were separated into seven fractions according to molecular size by normal-phase HPLC. The structure of each oligosaccharide thus isolated was analyzed by reversed-phase HPLC and characterized by ion-spray mass spectrometry and high-resolution proton nuclear magnetic resonance (1H-NMR) spectroscopy. Our results indicate that the asparagine-linked oligosaccharides of rat liver cathepsin L are of the oligomannose type, having two to six mannose residues. Among them, the five major ones are Manalpha1-6Manbeta1-4-GlcNAcbeta1-4GlcNAc, Manalpha1 -6Manalpha1-6Manbeta1-4GIcNAcbeta1-4GlcNAc, Manalpha1-6(Manalpha1-3)-Manalpha1-6Manbeta1- 4GlcNAcbeta1-4GlcNAc, Manalpha1-6(Manalpha1-3)Manalpha1-6(Manalpha1-3) Manbeta1-4Glc-NAcbeta1-4GlcNAc, and Manalpha1-6(Manalpha1-3)Manalpha1-6(Manalpha1-++ +2Manalpha1-3)Manbeta1-4GlcNAcbeta1-4Glc-NAc. Their structures are shown to be products of Man6GlcNAc2 hydrolysis with lysosomal alpha-mannosidase.
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PMID:The structures of asparagine-linked oligosaccharides of rat liver cathepsin L reflect the substrate specificity of lysosomal alpha-mannosidase. 974 60

The enormous complexity, wide dynamic range of relative protein abundances of interest (over 10 orders of magnitude), and tremendous heterogeneity (due to post-translational modifications, such as glycosylation) of the human blood plasma proteome severely challenge the capabilities of existing analytical methodologies. Here, we describe an approach for broad analysis of human plasma N-glycoproteins using a combination of immunoaffinity subtraction and glycoprotein capture to reduce both the protein concentration range and the overall sample complexity. Six high-abundance plasma proteins were simultaneously removed using a pre-packed, immobilized antibody column. N-linked glycoproteins were then captured from the depleted plasma using hydrazide resin and enzymatically digested, and the bound N-linked glycopeptides were released using peptide-N-glycosidase F (PNGase F). Following strong cation exchange (SCX) fractionation, the deglycosylated peptides were analyzed by reversed-phase capillary liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Using stringent criteria, a total of 2053 different N-glycopeptides were confidently identified, covering 303 nonredundant N-glycoproteins. This enrichment strategy significantly improved detection and enabled identification of a number of low-abundance proteins, exemplified by interleukin-1 receptor antagonist protein (approximately 200 pg/mL), cathepsin L (approximately 1 ng/mL), and transforming growth factor beta 1 (approximately 2 ng/mL). A total of 639 N-glycosylation sites were identified, and the overall high accuracy of these glycosylation site assignments as assessed by accurate mass measurement using high-resolution liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR) is initially demonstrated.
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PMID:Human plasma N-glycoproteome analysis by immunoaffinity subtraction, hydrazide chemistry, and mass spectrometry. 1633 52