scholarly journals Purification and characterization of glucosidase II involved in N-linked glycoprotein processing in bovine mammary gland

1987 ◽  
Vol 247 (3) ◽  
pp. 563-570 ◽  
Author(s):  
S Saxena ◽  
K Shailubhai ◽  
B Dong-Yu ◽  
I K Vijay

Glucosidase II is an endoplasmic-reticulum-localized enzyme that cleaves the two internally alpha-1,3-linked glucosyl residues of the oligosaccharide Glc alpha 1----2Glc alpha 1----3Glc alpha 1----3Man5-9GlcNAc2 during the biosynthesis of asparagine-linked glycoproteins. We have purified this enzyme to homogeneity from the lactating bovine mammary gland. The enzyme is a high-mannose-type asparagine-linked glycoprotein with a molecular mass of approx. 290 kDa. Upon SDS/polyacrylamide-gel electrophoresis under reducing conditions, the purified enzyme shows two subunits of 62 and 64 kDa, both of which are glycosylated. The pH optimum is between 6.6 and 7.0. Specific polyclonal antibodies raised against the bovine mammary enzyme also recognize a similar antigen in heart, liver and the mammary gland of bovine, guinea pig, rat and mouse. These antibodies were used to develop a sensitive enzyme-linked immunosorbent assay for glucosidase II.

1987 ◽  
Vol 247 (3) ◽  
pp. 555-562 ◽  
Author(s):  
K Shailubhai ◽  
M A Pratta ◽  
I K Vijay

Glucosidase I, the first enzyme involved in the post-translational processing of N-linked glycoproteins, was purified to homogeneity from the lactating bovine mammary tissue. The enzyme was extracted by differential treatment of the microsomal fraction with Triton X-100 and Lubrol PX. The solubilized enzyme was subjected to affinity chromatography on Affi-Gel 102 with N-5-carboxypentyldeoxynojirimycin as ligand and DEAE-Sepharose CL-6B chromatography. Purified glucosidase I shows a molecular mass of 320-330 kDa by gel filtration on Sephacryl S-300. SDS/polyacrylamide-gel electrophoresis under reducing conditions indicates a single band of approx. 85 kDa, indicating that the native enzyme is probably a tetrameric protein. Several criteria, including pH optimum of 6.6-7.0, specific hydrolytic action towards Glc3Man9GlcNAc2, to release the terminally alpha-1,2-linked glucosyl residue, and total lack of activity towards Glc1Man9GlcNAc2 and Glc2Man9GlcNAc2 saccharides, which are the biological substrates for processing glucosidase II, and 4-methylumbelliferyl alpha-D-glucopyranoside show the non-lysosomal origin and the processing-specific role of the purified enzyme. The enzyme does not require any metal ions for its activity. Hg2+, Ag+ and Cu2+ are potent inhibitors of the enzyme; this inhibition can be reversed by adding an excess of dithiothreitol. Among the saccharides tested, kojibiose (Glc alpha 1----2Glc) was inhibitory to the enzyme. Polyclonal antibodies raised against the enzyme in rabbit were found to be specific for glucosidase I, as revealed by Western-blot analysis and by immunoadsorption with Protein A-Sepharose. Anti-(glucosidase I) antibodies were cross-reactive towards a similar antigen in solubilized microsomal preparations from liver, mammary gland and heart from the bovine, guinea pig, rat and mouse.


Blood ◽  
1991 ◽  
Vol 77 (9) ◽  
pp. 1964-1969 ◽  
Author(s):  
F Flug ◽  
R Espinola ◽  
LX Liu ◽  
C SinQuee ◽  
R DaRosso ◽  
...  

Abstract We confirm the recent report (J Clin Invest 83:1778, 1989) of a polymorphism at amino acid 33 of platelet GPIIIa associated with the PLA1/PLA2 phenotype by using the polymerase chain reaction on cDNA derived from platelet RNA, using the base-pair primers 105–129 and 452- 428. Platelet cDNA from three PLA2-homozygous individuals, when digested with Nci I, gave two bands of 256 bp and 91 bp, whereas eight PLA1 cDNAs gave a single band of 347 bp. Two 13-mer amino acid peptides straddling the amino acid polymorphism: SDEALP (L/P) GSPRCD were synthesized for epitope studies. Two mouse polyclonal antibodies were raised: one against the PLA1-associated peptide, the other against the PLA2 peptide. Both antibodies react with either peptide, as well as with both PLA1 and PLA2 platelets. The PLA1 peptide did not block the binding of two different human anti-PLA1 antibodies to the 100-Kd GPIIIa band on immunoblot of platelet extracts; neither did it block the binding of the same antibodies to PLA1-platelet extracts in an enzyme-linked immunosorbent assay. Further studies were performed on the PLA1 epitope following subtilisin digestion of purified GPIIIa. A 55-Kd fragment was obtained that retained the PLA1 epitope as well as the first 13 N-terminal amino acids of GPIIIa. Reduction of the 55-Kd fragment resulted in loss of the PLA1 epitope with production of a 67- Kd, 21-Kd, and 10-Kd band on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The 55-Kd band does not react with LK-2, a monoclonal antibody versus GPIIIa that inhibits adenosine diphosphate, collagen, epinephrine, and thrombin-induced aggregation. Thus, the PLA1 epitope is conformation-induced, resides on an N-terminal 55-Kd fragment composed of two or more peptides held together by -SH bonds, and is not required for platelet aggregation.


1996 ◽  
Vol 59 (9) ◽  
pp. 992-997 ◽  
Author(s):  
FENG-YIR YU ◽  
FUN S. CHU

Polyclonal antibodies against fumonisin B1 (FmB1) were produced in rabbits after immunizing the animals with either FmBl-keyhole limpet hemocyanin (KLH) or FmB1 bovine serum albumin (BSA). A direct competitive enzyme-linked immunosorbent assay (dc-ELISA) and an indirect competitive ELISA (idc-ELISA) were used for the characterization of the antibodies and for analysis of the toxin in corn samples. The antibody titers in the serum of rabbits immunized with FmBl-KLH were considerably higher than in those immunized with FmBl-BSA. The antibodies from the rabbits immunized with FmBl-KLH were further characterized. The concentrations causing 50% inhibition of binding of FmB1-horseradish peroxidase (HRP) to the antibodies by FmB1, FmB2 and FmB3 in the ELISA were found to be 0.45, 0.72, and 25 ng/ml, respectively. The detection limit of FmBl, based on 95% confidence at 5% of inhibition of binding of FmBl-HRP conjugate, in buffer of the dc-ELISA was found to be 0.05 ng/ml. In the presence of a matrix such as corn, the detection limit was less than 50 ppb. The overall analytical recoveries of FmBl (50 to 1,000 ng/g) added to the ground corn and then extracted with CH3CN/H2O (1/1, vol/vol) with cleanup and without cleanup in the dc ELISA were found to be 70.5 and 85.9%, respectively. A good correlation was found between the FmBl levels in 2 starch and 10 naturally contaminated corn samples analyzed by the dc-ELISA and the high-pressure liquid chromatography (HPLC) method. The correlation coefficients between ELISA and HPLC were found to be 0.955 (y [ELISA] = 1.3 1x [HPLC] + 77 ppb; P < 0.001) and 0.811 (y = 1.13x + 34 ppb; P < 0.01) for the sample without and with cleanup treatment, respectively.


1987 ◽  
Vol 244 (1) ◽  
pp. 219-224 ◽  
Author(s):  
J M Jacobs ◽  
N J Jacobs

The protoporphyrinogen-oxidizing enzyme from Triton X-100 extracts of the mitochondrial and etioplast fractions of etiolated barley was purified by using ion-exchange and hydroxyapatite chromatography. The purified enzyme from both organelle fractions exhibited a Km of 5 microM and was labile to mild heat and acidification. The pH optimum (5-6) and the substrate-specificity (mesoporphyrinogen was oxidized as rapidly as protoporphyrinogen) revealed properties very different from the protoporphyrinogen-oxidizing enzyme of rat liver or yeast mitochondria, which is specific for protoporphyrinogen as substrate. The purest fractions showed a polypeptide band corresponding to an Mr of approx. 36,000 on SDS/polyacrylamide-gel electrophoresis. This is the first purification and characterization of the enzyme from a plant, and indicates no readily detectable differences between the enzyme isolated from mitochondrial or etioplast fractions, although only the latter organelle has the capacity for both haem and chlorophyll synthesis.


1989 ◽  
Vol 67 (8) ◽  
pp. 411-421 ◽  
Author(s):  
Om P. Malhotra

Isolation and characterization of γ-carboxyglutamic acid (Gla) deficient prothrombins induced by Warfarin or dicoumarol are useful for studying the role of specific Gla residues in prothrombin. In addition to 7-Gla prothrombin, we have isolated two more atypical prothrombins from the barium citrate eluate, one containing 6.11, and the other, 7.85 Gla residues, presumably 6- and 8-Gla prothrombins. The actual Gla content of the 7-Gla isomer was 7.05. Each of the 6-, 7-, and 8-Gla variants showed a single component by agar or dodecyl sulfate Polyacrylamide gel electrophoresis. When agar gel electrophoresis was performed in calcium, each of the variants moved more rapidly than normal (10-Gla) prothrombin. In the presence of EDTA, the 8-Gla isomer exhibited the fastest mobility, equivalent to that of normal prothrombin, followed by 7-, and then 6-Gla variants. The physiological activities of the isomers were found to be 18 to 23% for 8-, 6 to 8% for 7-, and 2 to 3% of normal prothrombin for 6-Gla variant. Prothrombin fragment 1, derived from 8-Gla prothrombin, exhibited 23% of calcium-induced fluorescence quenching, compared with 40% for 10-Gla and 8% or less for 7- and 6-Gla fragments 1. Competition radioimmunoassay data show that calcium-dependent anti (normal) prothrombin polyclonal antibodies are not specific for 10-Gla prothrombin, since the 7- and 8-Gla isomers were able to displace radiolabeled (125I) normal prothrombin.Key words: prothrombin, blood clotting, dicoumarol, Warfarin, γ-carboxyglutamic acid, vitamin K deficiency.


1998 ◽  
Vol 64 (12) ◽  
pp. 5033-5038 ◽  
Author(s):  
N. de Vries ◽  
K. A. Zwaagstra ◽  
J. H. J. Huis in’t Veld ◽  
F. van Knapen ◽  
F. G. van Zijderveld ◽  
...  

ABSTRACT Salmonella typhimurium expresses two antigenically distinct flagellins, each containing a different H antigen (i and 1,2), the combination of which is highly specific for this serotype. In this study, overlapping recombinant flagellin fragments were constructed from the fliC(H:i) and fljB (H:1,2) flagellin genes, and the expression products were tested for binding to H antigen-specific monoclonal and polyclonal antibodies. A minimal area, 86 amino acids for H:i and 102 amino acids for H:1,2, located in the central variable domain of each flagellin was required for the binding of serotype-specific antibodies, providing further evidence for the presence of a discontinuous H epitope. Two peptides comprising these areas were shown to be highly suitable for application as antigens in an enzyme-linked immunosorbent assay detecting S. typhimurium-specific antibody.


2013 ◽  
Vol 296 (12) ◽  
pp. 1943-1953 ◽  
Author(s):  
Melanie J. Millier ◽  
Kuljeet Singh ◽  
C. Anthony Poole

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