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)

A GALT-derived B lymphoma, T560, that bears IgAR is described. T560 is IgG2a kappa +, Ia+, B220+, J11d+, Thy-1-, CD3-, CD4-, CD5-, Mac 1-, Mac 2-, nonspecific esterase negative and binds bromelain-treated mouse RBC but not SRBC or ORBC. It presents antigen, secretes IL-1, IL-4 and IL-6 but not IL-2, IL-5 or TGF beta and appears to be related to the Lyt 1+(CD5) lineage of B cells though it lacks Lyt 1. T560 bears IgAR that, on the cell surface, are completely cross-inhibited by low concentrations of IgM and by high concentrations of IgG2a and IgG2b. They do not appear to represent a cell-surface form of galactosyl transferase. They are inducible by high concentrations of IgA, sensitive to trypsin and insensitive to neuraminidase. They are down-regulated by activation of PKC with PMA, but their recovery is not inhibited by cycloheximide, indicating that they are not degraded or shed. They may either lose their affinity for IgA or be internalized without degradation. Seventy percent of IgA receptor activity is lost when T560 is treated with PI-PLC; part of this loss of activity is due to activation of PKC and is inhibited by staurosporine, but approximately 30% of it is not protected by staurosporine indicating that some, or all, of the IgA receptor of T560 is connected to the cell membrane via a GPI linker. The T560 IgA receptor could be related to the poly-Ig or M cell receptor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sensitivity of receptors for IgA on T560, a murine B lymphoma, to phorbol myristate acetate and to phosphatidylinositol-specific phospholipase C. 165 5

Immunoglobulin fragments, whether of polyclonal or monoclonal antibodies, offer a number of advantages over the intact immunoglobulin. The generation of immunoreactive fragments from monoclonal antibodies (MAb) is not always a straightforward task. Both pepsin and papain can be used to digest MAb to a bivalent molecule with a Mr of 100,000. However, pepsin pepsin digestions does not always result in immunoreactive fragments and a stable consistent product by papain digestion is often difficult to obtain. MAb B72.3 is an example of both situations. MAb B72.3 reacts with a glycoprotein (TAG-72) with a molecular weight greater than 10(6). MAb B72.3 has been shown to exhibit a high degree of selective reactivity with colon, breast and ovarian carcinomas and has been used for radioimmunodiagnosis in model systems and in clinical trials. A third enzyme, bromelain, in the same family of sulfhydryl proteases as papain, has been used to generate a fragment of MAb B72.3, with a Mr of approximately 100,000. The bromelain-generated fragment of MAb B72.3 retained 100% immunoreactivity as measured in competitive solid-phase radioimmunoassays and could be generated with consistent results from one preparation to another. Both the bromelain- and papain-generated fragments were radiolabelled with 125I without significant loss of the MAb's reactivity to tumor extracts. Differences were observed between the bromelain- and papain-generated fragment when compared in vivo. Fragmentation of MAb B72.3 with bromelain has yielded a superior bivalent fragment for radioimmunolocalization.
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PMID:Comparison of methods for the generation of immunoreactive fragments of a monoclonal antibody (B72.3) reactive with human carcinomas. 249 38

In vitro treatment of human peripheral blood mononuclear cells (PBMNC) with proteolytic enzymes (bromelain, papain) and amylase leads to the production of large amounts of tumor necrosis factor-alpha (TNF-alpha), interleukin-1-beta (IL-1 beta), and interleukin-6 (IL-6) in a time and dose dependent manner. Increased TNF-alpha and IL-6 production was already found after 4-6 hours of incubation, and plateau levels were reached after 12-16 hours. Plateau levels up to 1500 pg TNF-alpha/ml/10(6) PBMNC, 13000 pg IL-1 beta/ml/10(6) PBMNC, and 23000 pg IL-6/ml/10(6) PBMNC were observed. Control cultures contained below 35 pg/ml/10(6) PBMNC of TNF-alpha, IL-1 beta or IL-6. In contrast to TNF-alpha which was undetectable after more than 24 hours, peak levels of IL-1 beta and IL-6 were still present at 24 hours. After incubation of the enzyme solution for some hours at 56 degrees C the cytokine inducing capacity disappeared. Neutralization experiments with inactivating antibodies, radioimmunoassay, and western blotting after electrophoretic separation showed that the TNF-like activity found in the lytic assay was due to TNF-alpha. Interferon-alpha (IFN-alpha) and Interferon-gamma (IFN-gamma), which had no effect alone, synergistically increased TNF-alpha production when applied together with the enzymes. A commercial mixture of these enzymes (Wobenzym), which was also investigated, showed a similar concentration and time dependence, as well as synergism with the interferons. A synergistic effect on TNF-alpha production was also found with the enzymes and phorbol ester (PMA).
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PMID:Proteolytic enzymes and amylase induce cytokine production in human peripheral blood mononuclear cells in vitro. 752 14

Recently, it has emerged that extracellular proteases have specific regulatory roles in modulating immune responses. Proteases may act as signaling molecules to activate the Raf-1/extracellular regulated kinase (ERK)-2 pathway to participate in mitogenesis, apoptosis, and cytokine production. Most reports on the role of protease-mediated cell signaling, however, focus on their stimulatory effects. In this study, we show for the first time that extracellular proteases may also block signal transduction. We show that bromelain, a mixture of cysteine proteases from pineapple stems, blocks activation of ERK-2 in Th0 cells stimulated via the TCR with anti-CD3epsilon mAb, or stimulated with combined PMA and calcium ionophore. The inhibitory activity of bromelain was dependent on its proteolytic activity, as ERK-2 inhibition was abrogated by E-64, a selective cysteine protease inhibitor. However, inhibitory effects were not caused by nonspecific proteolysis, as the protease trypsin had no effect on ERK activation. Bromelain also inhibited PMA-induced IL-2, IFN-gamma, and IL-4 mRNA accumulation, but had no effect on TCR-induced cytokine mRNA production. This data suggests a critical requirement for ERK-2 in PMA-induced cytokine production, but not TCR-induced cytokine production. Bromelain did not act on ERK-2 directly, as it also inhibited p21ras activation, an effector molecule upstream from ERK-2 in the Raf-1/MEK/ERK-2 kinase signaling cascade. The results indicate that bromelain is a novel inhibitor of T cell signal transduction and suggests a novel role for extracellular proteases as inhibitors of intracellular signal transduction pathways.
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PMID:Bromelain, from pineapple stems, proteolytically blocks activation of extracellular regulated kinase-2 in T cells. 1045 95