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)

An enzymatic procedure for the complete removal of the N-linked and O-linked oligosaccharide side chains of the sex steroid-binding proteins (SBP or SHBG) of human and rabbit plasma under native conditions is described. Deglycosylation was catalyzed by N-glycanase, neuraminidase, and O-glycanase and was monitored by SDS-PAGE, lectin blotting, and molecular weight analyses by electrospray mass spectrometry. Digestion of rabbit SBP with N-glycanase generated a major 39,777-Da protein and two minor ones of 39,389 and 39,545 Da. The molecular weight of the major protein agrees with the molecular weight calculated from the sequence of the sugar-free polypeptide monomer (39,769 Da: Griffin, P.R., Kumar, S., Shabanowitz, J., Charbonneau, H., Namkung, P.C., Walsh, K.A., Hunt, D.F., & Petra, P.H., 1989, J. Biol. Chem. 264, 19066-19075), whereas the other two are deglycosylated proteolytic cleavage products lacking the TQR and TQ sequences at the amino-terminus. The N- and O-linked side chains of human SBP were removed by sequential digestion with N-glycanase and neuraminidase/O-glycanase. A 38,771-Da protein was generated, which agrees well with the molecular weight of the sugar-free polypeptide monomer (Walsh, K.A., Titani, K., Kumar, S., Hayes, R., & Petra, P.H., 1986, Biochemistry 25, 7584-7590). N-deglycosylation of human and rabbit SBP has no effect on the steroid-binding activity, but removal of the O-linked side chains of N-deglycosylated human SBP results in an apparent 50% loss of steroid-binding activity and an increase in the Kd for the binding of 5 alpha-dihydrotestosterone from 0.3 mM to 0.9 nM.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Complete enzymatic deglycosylation of native sex steroid-binding protein (SBP or SHBG) of human and rabbit plasma: effect on the steroid-binding activity. 130 75

Soybean hull peroxidase (SBP, E.C. 1.11.1.7), an anionic glycoprotein, was found to contain 18.2% carbohydrate with the average composition: 2 mol GlcNAc, 3.3 mol Man, 0.9 mol Fuc, and 0.7 mol Xyl. The oligosaccharides of SBP, after release with glycopeptidase A, were investigated by a combination of high pH anion exchange chromatography with pulsed amperometric detection, methylation analysis and matrix assisted laser desorption/ionization-time-of-flight mass spectrometry. The structure of the major oligosaccharide, accounting for 60 to 65% of the total, is Man alpha 1-->6(Man beta 1-->3)(Xyl beta 1-->2)Man beta 1-->4GlcNAc beta 1-->4(Fuc alpha 1-->3)GlcNAc. A further 20 to 25% of the released oligosaccharides belong to the (Xyl)xManm(Fuc)fGlcNAc2 (m = 2, 4, 5, 6; f = 0 or 1, x = 0 or 1) family. The rest of the oligosaccharides were of the high-mannose type. Investigation of the six tryptic fractions containing carbohydrate revealed considerable heterogeneity in the N-linked oligosaccharides present in each fraction. The major glycan (4, Table III) was present in each fraction. Two of the fractions contained the major part of the high-mannose type glycans, ManmGlcNAc2 (m = 5-9), the major species being Man7GlcNAc2. The other four fractions contained mainly members of the (Xyl)xManm(Fuc)fGlcNAc2 (m = 2, 4, 5, 6; f = 0 or 1; x = 0 or 1) family. Methylation analysis of the holo- and apo-SBP provide support for the structures proposed for the oligosaccharides as well as for the heterogeneity of the glycopeptide fractions.
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PMID:The glycans of soybean peroxidase. 899 5

Tryptic digestion of apo-soybean peroxidase (apo-SBP), with and without acetamidation, chromatographic separation of the tryptic fragments and MALDI-TOF analysis of the major components, both before and after digestion with glycopeptidase A, demonstrated the presence of six carbohydrate groups on five peptides. Five of the glycopeptides can be mapped with confidence to the peptides containing Asn16, Asn90, Asn104, Asn169, and Asn174. The sixth N-glycosylation site is not known and does not appear to be Asn145. It may be present on the N-terminus of SBP, which has not been sequenced.
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PMID:The N-glycosylation sites of soybean seed coat peroxidase. 925 49