Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A colourimetric enzyme-linked sandwich assay has been developed to investigate the binding of human platelets to fibrinogen. The presence of platelets bound to fibrinogen-coated plastic can easily be detected and quantitated. Platelets treated with chymotrypsin to expose the fibrinogen receptor, are fixed with paraformaldehyde, and stored frozen. The detection sandwich consists of a mouse monoclonal antibody directed against the human platelet CD9 antigen, and a rabbit anti-mouse immunoglobulin conjugated to the enzyme alkaline phosphatase. The cleavage of the phosphatase substrate p-nitrophenyl phosphate can be monitored colourimetrically. The data presented provide evidence that this method is capable of detecting platelet-fibrinogen binding in a physiologically relevant manner. The binding is inhibited by EDTA or excess fibrinogen. The fibrinogen alpha and gamma chain peptides, RGDS and LGGAKQAGDV, and the snake venom echistatin are also inhibitory with IC50 values of 135 microM, 1.8 mM and 100 nM respectively.
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PMID:A colourimetric enzyme-linked sandwich assay for the detection of human platelets bound to a fibrinogen-coated surface. 189 64

In view of the fact that trypsin enhances the infectivity of human rotavirus and decreases its hemagglutination, the trypsin-mediated structural modification of the viral polypeptides was analysed, using the KUN strain, a cultivable human rotavirus isolate, grown in the absence of trypsin. A major polypeptide sensitive to trypsin treatment was Vp4 with a molecular weight of 80,000, being cleaved into three polypeptides with molecular weights of 54,000 (P54), 30,000 (P30), and 24,000 (P24). Vp4 was also sensitive to chymotrypsin treatment, generating cleavage products different from those obtained with trypsin.
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PMID:Effect of trypsin and chymotrypsin on polypeptides of human rotavirus KUN strain. 303 57

Infection of monocyte-macrophages with human immunodeficiency virus may be central to the pathogenesis of the acquired immunodeficiency syndrome. The ability of infected macrophages to prime T cells through IL-1 production was investigated in vitro. Purified human monocytes maintained in suspension culture were infected with strain HIV-DV. Intracellular expression of virus p24 antigen increased from undetectable levels immediately after infection to 13-59% of cells by 10-14 d; infected macrophages remained viable for up to 60 d. Supernatants collected between 14 and 20 d after infection were examined in the murine thymocyte co-mitogenesis assay and demonstrated to contain a potent IL-1 inhibitor, designated contra-IL-1. Contra-IL-1 activity was present in all supernatants examined after 4 d of infection, and peaked coincident with peak p24 antigen expression. Inhibitory activity was not present in uninfected cells. Contra-IL-1 activity eluted after gel filtration with an approximate molecular weight of 9 kD. Inhibitory activity was removed by exposure to heat or acid pH, or by incubation with chymotrypsin or staphylococcal V8 protease. Contra-IL-1 did not inhibit IL-2- or IL-4-dependent proliferation of murine T cell lines. Despite its ability to inhibit IL-1 activity, contra-IL-1 did not interfere with the binding of recombinant IL-1 beta to a fibroblast cell line. Contra-IL-1 inhibited the proliferation of normal peripheral blood mononuclear cells to both concanavalin A and tetanus toxoid; inhibition could be attenuated by the addition of exogenous IL-1. Messenger RNA extracted from infected macrophages was examined by Northern analysis for the presence of message to IL-1 beta. No message was apparent, suggesting that the presence of contra-IL-1 was not obscuring the concomitant release of IL-1. Infected macrophages stimulated with endotoxin generated readily detectable message for IL-1 beta. Spleen macrophages purified from two patients with AIDS complicated by immune thrombocytopenia spontaneously expressed p24 antigen in vitro and released contra-IL-1 activity into the media. Contra-IL-1 may contribute to the immune dysfunction of AIDS.
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PMID:Release of interleukin 1 inhibitory activity (contra-IL-1) by human monocyte-derived macrophages infected with human immunodeficiency virus in vitro and in vivo. 326 91