Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.32 (bromelain)
 1,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glycosylation is one of the major naturally occurring covalent modifications of proteins. We have used stem bromelain, a thiol protease with a single, N-glycosylated polypeptide chain as a model to investigate the role of glycosylation of proteins. Periodate oxidation was used to obtain the deglycosylated form of the enzyme. Denaturation studies in the presence of guanidine hydrochloride (Gn*HCl) were performed using fluorescence and circular dichroism spectroscopy. The glycosylated stem bromelain was found to be stabilized by 1.9 kcal/mol as compared to the deglycosylated one. At a given concentration of denaturant, the fraction of denatured protein was higher in the case of deglycosylated stem bromelain. In short, deglycosylated bromelain showed more susceptibility towards guanidine hydrochloride denaturation, indicating the contribution of the carbohydrate part of the glycoprotein to the stability of the enzyme.
 ...
PMID:Guanidine hydrochloride denaturation of glycosylated and deglycosylated stem bromelain. 1461 80

The biological significance of the carbohydrate moiety of a glycoprotein has been a matter of much speculation. In the present work, we have chosen stem bromelain from Ananas comosus as a model to investigate the role of glycosylation of proteins. Stem bromelain is a thiol protease which contains a single hetero-oligosaccharide unit per molecule. Here, the deglycosylated form of the enzyme was obtained by periodate oxidation. The differences in the glycosylated and deglycosylated forms of the glycoprotein have been studied at various temperatures and pH values, using probes such as loss of enzyme activity and by the changes in fluorescence and circular dichroism spectra. Deglycosylated bromelain showed decreased enzyme activity and perturbed fluorescence and circular dichroism spectra. In addition to this, a comparative study of their activities in different organic solvents showed a marked decrease in case of deglycosylated form of the enzyme. It is thus concluded that glycosylation contributes towards the functional stability of glycoenzymes.
 ...
PMID:Effect of pH, temperature and alcohols on the stability of glycosylated and deglycosylated stem bromelain. 1466 Aug 70

Influenza C virus contains a single surface glycoprotein in its lipid envelope which is the hemagglutinin-esterase-fusion glycoprotein (HEF). HEF binds cell-surface receptors, is a receptor-destroying enzyme (a 9-O-acetylesterase), and mediates the fusion of virus and host cell membranes. A bromelain-released soluble form of HEF has been crystallized. Two different tetragonal forms have been identified from crystals with the same morphology [P(1(3))22, a = b = 154.5, c = 414.4 A, and P4(1(3))2(1)2, a = b = 217.4, c = 421.4 A]. Both crystal forms share a common packing scheme. Synchrotron data collection and flash cooling of crystals have been used for high-resolution data collection.
 ...
PMID:Crystallization and preliminary X-ray diffraction studies of the influenza C virus glycoprotein. 1529 21

A glycan-related IgE-reactivity has been demonstrated in most allergen sources, especially in plant kingdom. Recent progress in glycobiology has allowed a clearer classification of these glyco-epitopes. Unlike classical peptide chain-based epitopes, glyco-epitopes can share significant structural homologies beyond the limits of protein families. These glycoepitopes are thus prone to extensive cross-reactivity. They have been called Cross-reactive Carbohydrate Determinants or CCD. Many of these glyco-epitopes behave as "panepitopes", leading to cross-reactivity between products as distant as pollens and hymenoptera venoms. But CCD are not universally cross-reactive and they rather cluster into subgroups such as plant CCD or fungal CCD. Because a monovalent IgE-binding is sufficient in serum-based assays, glyco-epitopes and CCD are classically considered as a potential source of positive in vitro results without clinical significance. But some authors recently demonstrated that glyco-epitopes could induce a response at the cell level and suggested that they might play a role in vivo. As long as in vitro assays include glycan- and CCD-related IgE responses, laboratory results should be carefully interpreted in the light of existing knowledge about the glycomes of natural products. IgE-reactivity of the patient's serum can also be tested towards a glycoprotein model such as bromelain.
 ...
PMID:IgE-reactive carbohydrate epitopes--classification, cross-reactivity, and clinical impact. 1591 12

Protoplasts and vacuoles were isolated and purified in large numbers from the CAM plants Ananas comosus (pineapple) and Sedum telephium for protein characterization. Vacuoles were further fractionated to yield a tonoplast vesicle preparation. Polypeptides of protoplasts, vacuoles, and tonoplast vesicles were compared to whole leaf polypeptides from both plants by one-dimensional sodium dodecylsulfate-polyacrylamide gel electrophoresis. Approximately 100 vacuole polypeptides could be resolved of which 25 to 30% were enriched in the tonoplast vesicles. The proteins of protoplasts, vacuoles, and tonoplast vesicles from A. comosus were analyzed further by two-dimensional gel electrophoresis. When one-dimensional electrophoretograms of A. comosus polypeptides were stained with a glycoprotein-specific periodic acid Schiff stain, very few polypeptides appeared to be glycosylated, whereas a large number of glycosylated polypeptides were detected with a silver-based glycoprotein stain particularly in tonoplast vesicles. Analysis of the enzymic content of vacuoles from both plants indicated the presence of a variety of hydrolases, including bromelain as a major constituent of A. comosus. No substrate-specific ATPase, however, could be detected in vacuoles or tonoplast vesicles from either plant.
 ...
PMID:Electrophoretic analysis of protoplast, vacuole, and tonoplast vesicle proteins in crassulacean Acid metabolism plants. 1666 66

The proteolysis of flu virions of the strain A/Puerto Rico/8/34 (subtype H1N1) by enzymes of various classes was studied to develop an approach to the study of the structural organization and interaction of the basic protein components of the virion environment: hemagglutinin (HA), transmembrane homotrimeric glycoprotein, and matrix protein M1 forming a layer under the lipid membrane. Among the tested proteolytic enzymes and enzymic preparations (thermolysin, trypsin, chymotrypsin, subtilisin Carlsberg, pronase, papain, and bromelain), the cysteine proteases bromelain and papain and the enzymic preparation pronase efficiently deleted HA ectodomains, while chymotrypsin, trypsin, and subtilisin Carlsberg deleted only a part of them. An analysis by MALDI TOF mass spectrometry allowed us to locate the sites of HA hydrolysis by various enzymic preparations. Bromelain, papain, trypsin, and pronase split the polypeptide chain after the K177 residue located before the transmembrane domain (HA2 185-211). Subtilisin Carlsberg hydrolyzed the peptide bond at other neighboring points: after L178 (a basic site) or V176. The hydrolytic activity of bromelain measured by a highly specific chromogenic substrate of cysteine proteases Glp-Phe-Ala-pNA was almost three times higher in the presence of 5 mM beta-mercaptoethanol than in the presence of 50 mM. However, the complete removal of exodomains of HA, HA, and low-activity enzyme by the HA high- and low-activity enzyme required identical time intervals. In the absence of the reducing reagent, the removal of HA by bromelain proceeded a little more slowly and was accompanied by significant fragmentation of protein Ml1. The action of trans-epoxysuccinyl-L-leucylamido)butane (E-64), a specific inhibitor of cysteine proteases, and HgCl2 on the hydrolysis of proteins HA and M1 by bromelain was investigated.
 ...
PMID:[Flu virion as a substrate for proteolytic enzymes]. 1867 93

Lymphoproliferative disease virus, a recently isolated C-type retro-virus, cannot yet be cultured in cells in vitro and rarely induces a high titre virus-specific antiserum. However, after digestion of purified virus with bromelain and rebanding the treated virus in sucrose gradients bald virions devoid of the viral spike glycoprotein and up to 20 host proteins were found to induce a high level virus-specific antibody response in rabbits and chickens.
 ...
PMID:Production of virus-specific antisera to lymphoproliferative disease virus of turkeys. 1876 56

Influenza A virus matrix M1 protein is membrane associated and plays a crucial role in virus assembly and budding. The N-terminal two thirds of M1 protein was resolved by X-ray crystallography. The overall 3D structure as well as arrangement of the molecule in relation to the viral membrane remains obscure. Now a proteolytic digestion of virions with bromelain was used as an instrument for the in situ assessment of the M1 protein structure. The lipid bilayer around the subviral particles lacking glycoprotein spikes was partially disrupted as was shown by transmission electron microscopy. A phenomenon of M1 protein fragmentation inside the subviral particles was revealed by SDS-PAGE analysis followed by in-gel trypsin hydrolysis and MALDI-TOF mass spectrometry analysis of the additional bands. Putative bromelain-digestion sites appeared to be located at the surface of the M1 protein globule and could be used as landmarks for 3D molecular modeling.
 ...
PMID:Influenza A virus M1 protein structure probed by in situ limited proteolysis with bromelain. 1899 68

The density of distribution of glycoproteins on virion surface seriously influences the virus infectivity and pathogenicity. In the present work a method of quantitative determination of the area occupied by the surface glycoprotein spikes is proposed for influenza virus (strain A/PR/8/34) based on data of tritium bombardment and dynamic light scattering (DLS). The method of DLS was used for measuring the diameter of the intact virions and the subviral particles (influenza virions lacking glycoprotein spikes after bromelain digestion). The intact virions and the subviral particles were bombarded by the hot tritium atom flux followed by the analysis of the specific radioactivity of the matrix M1 protein. It was shown that the tritium label was incorporated into the amino acid residues of a thin exposed protein layer and partially penetrated through the lipid bilayer of the viral envelope. As a result, the matrix M1 protein which is located under the lipid bilayer became labeled. The tritium label distribution among different amino acid residues was the same for the M1 protein isolated from the subviral particles and the one isolated from the intact virions. This testifies that the M1 protein spatial structure remains unchanged during proteolysis of the glycoprotein spikes. The difference between the specific radioactivity of the M1 protein isolated from the intact virions and that of the M1 protein isolated from the subviral particles allowed us to calculate the portion of the viral surface which is free of the glycoprotein spikes. If approximate the influenza virion as as here the area occupied by the surface glycoproteins could be calculated. It appeared to be equal to approximately 1.4 yen 10 nm that is about 40% of the total viral surface. This is consistent with the cryoelectron tomography data published for the influenza virus (strain A/X-31). The developed approach could be applied for other enveloped high pathogenic viruses such as HIV and Ebola.
 ...
PMID:[An approach the quantitative determination of the area of glycoprotein spikes at the surface of enveloped viruses]. 1914 Mar 31

Bovine adenovirus serotype 3 (BAd3) and porcine adenovirus serotype 3 (PAd3) entry into the host cells is independent of Coxsackievirus adenovirus receptor and integrins. The role of sialic acid in BAd3 and PAd3 entry was investigated. Removal of sialic acid by neuraminidase, or blocking sialic acid by wheat germ agglutinin lectin significantly inhibited BAd3, but not PAd3, transduction of Madin-Darby bovine kidney cells. Maackia amurensis agglutinin or Sambucus nigra (elder) agglutinin treatment efficiently blocked BAd3 transduction suggesting that BAd3 utilized alpha(2,3)-linked and alpha(2,6)-linked sialic acid as a cell receptor. BAd3 transduction of MDBK cells was sensitive to sodium periodate, bromelain, or trypsin treatment indicating that the receptor sialoconjugate was a glycoprotein rather than a ganglioside. To determine sialic acid-containing cell membrane proteins that bind to BAd3, virus overlay protein binding assay (VOPBA) was performed and showed that sialylated cell membrane proteins in size of approximately 97 and 34 kDa bind to BAd3. The results suggest that sialic acid serves as a primary receptor for BAd3.
 ...
PMID:Bovine adenovirus serotype 3 utilizes sialic acid as a cellular receptor for virus entry. 1964 29


<< Previous 1 2 3 4 5 6 Next >>