Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.5.1.4 (deaminase)
5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase F (PNGase F) is an amidase that cleaves the beta-aspartylglucosylamine bond of asparagine-linked glycans. The 34.8-kDa (314 amino acids) enzyme has a very broad substrate specificity and is extensively used for studies of the structure and function of glycoproteins. Enzymatic activity of PNGase F requires recognition of both the peptide and the carbohydrate components of the substrate. Only limited information regarding the mechanism of action of the enzyme is available. The three-dimensional structure of PNGase F has been determined by X-ray crystallography at 2.2-A resolution. The protein folds into two domains comprising residues 1-137 and 143-314, respectively. Both domains have eight-stranded antiparallel beta-sandwich motifs that are very similar in geometry. Both sandwiches have parallel principal axes and lie side by side. The covalent link between the domains is located at the top end of the molecule. Extensive hydrogen-bonding contacts occur along the full length of the interface between the two domains. Three different areas, all at the interface between the two domains, have been identified as possible locations for the active site of the enzyme. These include a hydrophobic bowl of about 20 A in diameter on one surface of the molecule, a long polar cleft on the opposite side, and a cleft at the bottom, which is lined with large aromatic residues including eight tryptophans.
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PMID:Crystal structure of peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase F at 2.2-A resolution. 791 86

In the present study, we investigated the nature and the importance of glycosylation of two mammalian bombesin receptors, the neuromedin B receptor (NMB-R) and the gastrin-releasing peptide receptor (GRP-R), using chemical cross-linking and enzymatic deglycosylation. [125I]-(D-Tyr0)NMB cross-linked to native NMB-R on rat C-6 glioblastoma cells or rat NMB-R transfected into BALB 3T3 cells revealed a single broad band, M(r) = 63,000, on both cell types that was not altered by DTT. NMB inhibited cross-linking specifically and saturably with an IC50 of 4.8 and 6.1 nM for C-6 and NMB-R transfected cells, respectively, and there was a close correlation between its ability to inhibit binding and its ability to inhibit cross-linking. A single broad band of M(r) = 82,000 was cross-linked with [125I]GRP on mouse GRP-R transfected BALB 3T3 cells. Peptide-N4-(N-acetyl-beta- glucosaminyl)asparagine amidase F (PNGase F) digestion increased the mobility of the original band in C-6, NMB-R, and GRP-R transfected cell membranes. Endoglycosidase H (Endo-H) and endoglycosidase F2 (Endo-F2) digestion had no effect on both transfected cells. Neuraminidase digestion slightly increased the mobility of the original band in NMB-R transfected cell membranes; however, it had no effect on GRP-R transfected cell membranes. Endo-alpha-N-acetylglucosaminidase (O-glycanase) digestion subsequent to neuraminidase treatment showed no additional effect on either receptor. Serial partial deglycosylation of cross-linked NMB-Rs with PNGase F treatment for different incubation periods revealed one band of partially glycosylated receptor (53 kDa) besides the fully glycosylated and fully deglycosylated ones, showing that NMB-R has two oligosaccharide chains. Similarly, three partially deglycosylated species (72, 62, and 52 kDa) are seen with the GRP-R, indicating that the GRP-R has four oligosaccharide chains. Treatment of unlabeled membranes with PNGase F followed by affinity labeling resulted in fully deglycosylated NMB-R or 75% deglycosylated GRP-R. Deglycosylation of the NMB-R did not alter its affinity for NMB or alter G-protein coupling; however, 75% deglycosylation of the GRP-R both decreased its affinity for GRP and altered its ability to couple to G-proteins. The present results demonstrate that NMB-R on native and transfected cells is an N-linked sialoglycoprotein with two triantenary and/or tetraantenary complex oligosaccharide chains. The apparent M(r) of this sialoglycoprotein is 63,000, and this protein does not contain disulfide-linked subunits or O-linked carbohydrates.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Glycosylation of bombesin receptors: characterization, effect on binding, and G-protein coupling. 794 1

We previously reported the occurrence of oligomannosides and xylomannosides corresponding to unconjugated N-glycans (UNGs) in the medium of a white campion (Silene alba) cell suspension. Attention has been focused on these oligosaccharides since it was shown that they confer biological activities in plants. In an attempt to elucidate the origin of these oligosaccharides, we studied two endoglycosidase activities, putative enzymes involved in their formation. The previously described peptide-N4-(N-acetyl-glucosaminyl) asparagine amidase activity and the endo-N-acetyl-beta-D-glucosaminidase activity described in this paper were both quantified in white campion cells during the culture cycle with variable initial concentrations of sucrose. The lower the sucrose supply, the higher the two activities. Furthermore, endoglycosidase activities were greatly enhanced after the disappearance of sugar from the medium. The production of UNGs in the culture medium rose correlatively. These data strongly suggest that the production of UNGs in our white campion cell-suspension system is due to the increase of these endoglycosidase activities, which reach their highest levels of activity during conditions of carbon starvation.
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PMID:Carbon starvation increases endoglycosidase activities and production of "unconjugated N-glycans" in Silene alba cell-suspension cultures. 799 89

We previously showed that under defined conditions beta-[3H]funaltrexamine (beta-[3H]FNA) covalently labeled mu-opioid receptors with high specificity in bovine striatal membranes. beta-[3H]FNA-labeled mu-opioid receptors migrated as a broad band with a molecular mass range of 68-97 kDa. It is controversial whether beta-FNA binds irreversibly to mu-opioid receptors in other species. In this study, we demonstrated that beta-[3H]FNA also labeled mu-opioid receptors with high specificity in brain membranes of the guinea pig, rat, and mouse. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography revealed that in each species beta-[3H]FNA specifically bound to a protein in which labeling was greatly reduced by naloxone. These labeled receptors had broad molecular mass ranges, and the molecular masses were different among these species, in the order of cow > guinea pig > rat > mouse. Membranes were subjected to solubilization with 2% Triton X-100 and wheat germ lectin (WGL) affinity chromatography. N-Acetylglucosamine eluted a peak of radioactivity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography showed that in all four species the mu receptor was the only protein labeled with beta-[3H]FNA in the WGL eluate. The molecular masses of labeled mu-opioid receptors were 70-88 kDa (median, 77 kDa) for the cow, 66-80 kDa (median, 72 kDa) for the guinea pig, 60-75 kDa (median, 67 kDa) for the rat, and 60-72 kDa (median, 66 kDa) for the mouse. In addition, we investigated the nature of the carbohydrate moieties linked to the receptor protein and whether the species variation in the molecular mass was due to variable degrees of glycosylation. The bovine WGL eluate was treated with various glycosidases. Neuraminidase treatment decreased the receptor molecular mass by 6-7 kDa, whereas alpha-mannosidase had no effect. Removal of N-linked carbohydrates at asparagine residues by peptide-N4-[N-acetyl-beta-glucosaminyl]asparagine amidase (N-Glycanase) resulted in a much sharper specifically labelled protein band of 43 kDa. These results indicate that mu-opioid receptors are heavily glycosylated and the major carbohydrate moieties are of the complex type, N-linked to asparagine. After the WGL eluates for the four species were treated with N-Glycanase, the labeled receptors became much sharper bands with very similar molecular masses, i.e., 43 kDa for the cow and guinea pig, 39 kDa for the rat, and and 40 kDa for the mouse.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Beta-[3H]funaltrexamine-labeled mu-opioid receptors: species variations in molecular mass and glycosylation by complex-type, N-linked oligosaccharides. 823 25

The vasoactive intestinal peptide (VIP) receptor from the human melanoma cell line IGR39 has been shown to be a 60-kDa glycoprotein. Using serial lectin affinity chromatography, as well as specific glycosidases, we demonstrate that VIP receptor-linked carbohydrates are predominantly tri- or tetraantennary sialylated N-linked oligosaccharides, 27% of which are fucosylated, and some may have terminal galactose residues. Treatment of 125I-VIP receptor complexes with peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase revealed the presence of at least three N-linked carbohydrate chains/receptor polypeptide. To investigate the functional role of the carbohydrate moiety, 125I-VIP binding to IGR39 cell membranes was tested in the presence of soluble lectins. Among the lectins tested, only wheat germ agglutinin (WGA) was found to markedly inhibit VIP binding in a dose-dependent manner. Binding data indicated that the presence of the lectin led to a 3-fold increase in Kd value, from 0.15 to 0.44 nM, without any change in the number of available binding sites. The potent inhibitor of WGA binding, N,N',N"-triacetylchitotriose, completely reversed the effect of the lectin. On the other hand, VIP binding inhibition persisted even after neuraminidase treatment, suggesting that sialic acids were not directly involved. Furthermore, WGA inhibition was not abolished although most, if not all, VIP receptor oligosaccharides were converted to high mannose type structures by treating IGR39 cells with deoxymannojirimycin. Finally, whereas the pharmacological profile of VIP receptor was virtually identical, the presence of WGA greatly reduced the VIP-stimulated cAMP in IGR39 cells, indicating that the lectin alters the ability of the receptor to interact with the adenylate cyclase system.
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PMID:Structural and functional analysis of the human vasoactive intestinal peptide receptor glycosylation. Alteration of receptor function by wheat germ agglutinin. 838 3

We have developed an intermediate method toward the complete carbohydrate analysis of proteins, which should be universally applicable to all proteins and independent of sample matrix. Using only Coomassie Blue-stained proteins which have been electroblotted onto polyvinylidene fluoride membranes, we report a strategy for: (i) determining unequivocally whether a protein is glycosylated; (ii) obtaining a complete monosaccharide composition; (iii) oligosaccharide mapping which separates most forms according to size, charge and isomerity; and (iv) sequentially releasing and analyzing specific classes of oligosaccharides with endoglycosidases. The method was shown to be applicable to a variety of well characterized soluble glycoproteins and to the membrane-bound protein, the gastric H+, K(+)-ATPase. The monosaccharide composition of the H+,K(+)-ATPase revealed the absence of N-acetylneuraminic or N-glycolylneuraminic acids and a monosaccharide composition which indicated O-linked sugar chains. Oligomannosidic/hybrid and biantennary oligosaccharides were sequentially released and analyzed from one electroblotted band of recombinant tissue plasminogen activator using endo-beta-N-acetylglucosaminidase H and endo-beta-N-acetylglucosaminidase F2, respectively. Sialylated polylactosamine structures were identified and quantified by analyzing high performance liquid chromatography profiles of oligosaccharides first released by peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase and then treated with endo-beta-galactosidase, using a single, stained band of recombinant erythropoietin. This recombinant erythropoietin was found to contain eight times more tetrasialylated oligosaccharides than previously reported (Sasaki, H., Bothner, B., Dell, A., and Fukuda, M. (1987) J. Biol. Chem. 262, 12059-12076); 47% of released oligosaccharides were identified as polylactosamine structures.
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PMID:Monosaccharide and oligosaccharide analysis of proteins transferred to polyvinylidene fluoride membranes after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 844 88

Oligosaccharides on invertase restricted to the endoplasmic reticulum (ER) in alg3,sec18 yeast at 37 degrees C were found to be 20% wild type Man8GlcNAc and 80% Man1 alpha-->2Man1 alpha-->2Man1 alpha-->3(Man1 alpha-->6)Man1 beta-->4GlcNAc2 (Verostek, M.F., Atkinson, P.H., and Trimble, R. B. (1991) J. Biol. Chem. 266, 5547-5551). These results suggested that alg3 was slightly leaky, but did not address whether the oligosaccharide-lipid Man9GlcNAc2 and Man5GlcNAc2 precursors were glucosylated in alg3 yeast. Therefore, an alg3,sec18,gls1 strain was constructed to delete the GLS1-encoded glucosidase I responsible for trimming the terminal alpha 1,2-linked glucose from newly transferred Glc3ManxGlcNAc2 oligosaccharides. Invertase activity was overexpressed 5-10-fold on transforming this strain with a multicopy plasmid (pRB58) carrying the SUC2 gene, and preparative amounts of the ER form of external invertase, derepressed and accumulated at 37 degrees C, were purified. The N-linked glycans were released by sequential treatment with endo-beta-N-acetylglucosaminidase H (endo H) and peptide-N4-N-acetyl-beta-glucosaminyl asparagine amidase. Oligosaccharide pools were sized separately on Bio-Gel P-4, which showed that endo H released about 17% of the carbohydrate as Glc3Man8GlcNAc, while peptide-N4-N-acetyl-beta-glucosaminyl asparagine amidase released the remainder as Hex8GlcNAc2 and Man5GlcNAc2 in a 1:4 ratio. Glycan structures were assigned by 500-MHz two-dimensional DQF-COSY 1H NMR spectroscopy, which revealed that the endo H-resistant Hex8GlcNAc2 pool contained Glc3Man5GlcNAc2 and Man8GlcNAc2 in a 6:4 ratio, the latter a different isomer from that formed by the ER alpha 1,2-mannosidase (Byrd, J. C., Tarentino, A. L., Maley, F., Atkinson, P. H., and Trimble, R. B. (1982) J. Biol. Chem. 257, 14657-14666). Recovery of Glc3Man8GlcNAc and not the ER form of Man8GlcNAc provided an internal control indicating the absence of glucosidase I, which was confirmed by incubation of [3H]Glc3[14C]Man9GlcNAc with solubilized membranes from either alg3,sec18,gls1 or alg3,sec18,GLS1 strains. Chromatographic analysis of the products showed that [3H]Glc was removed only in the presence of the GLS1 gene product. Thus, the vast majority of the N-linked glycosylation in the ER of alg3 yeast (> 75%) occurs by transfer of Man5GlcNAc2 without prior addition of the 3 glucoses normally found on the lipid-linked precursor.
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PMID:Glycoprotein biosynthesis in the alg3 Saccharomyces cerevisiae mutant. I. Role of glucose in the initial glycosylation of invertase in the endoplasmic reticulum. 850 33

Alg3 yeast mutants synthesize endoglycosidase H-resistant oligosaccharides whose precursor for elongation is Man1 alpha-->2Man1 alpha-->2Man1 alpha-->3(Man1 alpha-->6)Man1 beta-->4GlcNAc2 (Verostek, M.F., Atkinson, P.H., and Trimble, R. B. (1991) J. Biol. Chem. 266, 5547-5551). To characterize alg3 glycan elongation in vivo, oligosaccharides on alg3,sec18 invertase synthesized and secreted at 26 degrees C were released with peptide-N4-N-acetyl-beta-glucosaminyl asparagine amidase and purified by Bio-Gel P-4 chromatography. Large (Man > 30GlcNAc2) and intermediate (Man5-10GlcNAc2) sized oligosaccharides were pooled separately, and the smaller ones were exchanged with 2H2O for one- and two-dimensional DQF-COSY 1H NMR analyses at 500 MHz. Although there was no detectable substitution of the terminal alpha 1,6-core-linked mannose, addition of alpha 1,6-, alpha 1,2-, and alpha 1,3-mannoses to the alpha 1,3-linked core branch of a majority of the Man5 precursor was analogous to core-filling reactions seen on wild type invertase glycans (Trimble, R.B., and Atkinson, P.H. (1986) J. Biol. Chem. 261, 9815-9824). Two additional types of oligosaccharide structures were found; those which retained glucose and those consistent with mannan elongation. Glucose retention appeared to be due to inefficient trimming from minor glucosylated intermediates, while mannan elongation was by extension of a new alpha 1,6-linked branch from the alpha 1,3-core-linked residue as seen in wild-type core oligosaccharides (Hernandez, L.M., Ballou, L., Alvarado, E., Gillece-Castro, B.L., Burlingame, A.L., and Ballou, C. E. (1989) J. Biol. Chem. 264, 11849-11856) or mnn1,mnn2,mnn10 processing intermediates (Ballou, L., Alvarado, E., Tsai, P-k., Dell, A., and Ballou, C.E. (1989) J. Biol. Chem. 264, 11857-11864). Thus, the alpha 1,6-linked branch additions which form Man9GlcNAc2-PP-dolichol from Man5GlcNAc2-PP-dolichol appear to provide important structural information enabling efficient recognition by the endoplasmic reticulum-glucosyltransferases forming oligosaccharide-lipid as well as the glucosidases involved in early trimming reactions, but the alg3 mutant documents that they are unnecessary for normal yeast mannan elongation.
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PMID:Glycoprotein biosynthesis in the alg3 Saccharomyces cerevisiae mutant. II. Structure of novel Man6-10GlcNAc2 processing intermediates on secreted invertase. 850 34

The asparagine-linked oligosaccharides from an adult female mouse submandibular gland mucin were released by treatment with peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase F or endo-beta-N-acetylglucosaminidase H. Endo-beta-N-acetylglucosaminidase H appeared to be more effective at releasing the asparagine-linked oligosaccharides from this mucin than was peptide-N4-(N-acetyl-beta-glucosaminyl)-asparagine amidase F. After quantitative reductive labelling with the fluorophore, 8-aminonaphthalene-1,3,6-sulphonic acid, the oligosaccharides were separated by polyacrylamide gel electrophoresis and isolated. The individual oligosaccharides were sequenced by a battery of recombinant exoglycosidases. Approximately 50% of the oligosaccharides were of the high-mannose type. The five-mannose member of this family was the most prevalent. The second group of oligosaccharides were of the non-bisected hybrid type. No complex asparagine-linked oligosaccharides were detected. The hybrids exhibited both biantennary and triantennary branching patterns. The triantennary hybrid was the most common hybrid at > 30% of all oligosaccharides. With approximately 98% of the hybrid oligosaccharides sialylated and all lacking a bisecting N-acetylglucosamine, these oligosaccharides as a group have been only rarely observed in other glycoproteins. The fully sialylated triantennary hybrid may be unique.
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PMID:Characterization of asparagine-linked oligosaccharides on a mouse submandibular mucin. 856 46

Horseradish peroxidase isoenzyme C (HRP) contains eight N-linked glycans composed of Man, Xyl, Fuc, and GlcNAc. These glycans were resistant to enzymatic hydrolysis by endoglycosidases peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase F, endo-beta-N-acetyl-glucosaminidase H, and endo-beta-N-acetylglucosaminidase F under conditions where ovalbumin was deglycosylated. However, using anhydrous trifluoromethanesulfonic acid (TFMS) in the presence of 90 mM phenol for 5 min at--10 degrees C, all carbohydrate except GlcNAc was removed. Sixty percent of deglycosylated HRP was active after this TFMS treatment. Benzhydroxamic acid affinity chromatography separated active and inactive deglycosylated HRP. TFMS treatment, however, introduced negative charges in all inactive HRP and in about 90% of the active deglycosylated HRP. The nature of this modification has not been identified. After ion-exchange chromatography, homogeneous and fully active deglycosylated HRP, showing the original pI of 9, electronic absorption spectrum, and enzyme kinetics, was obtained, In this purified product no amino acid modifications were detected by amino acid analysis, partial sequencing, and mass spectrometry of tryptic peptides. The deglycosylated product showed greatly reduced solubility in salt solution compared to that of authentic HRP.
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PMID:Mild chemical deglycosylation of horseradish peroxidase yields a fully active, homogeneous enzyme. 857 87


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