Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nature of specific adherence of rat anti-TNP PFC to TNP-GRBC has been investigated with PLL-fixed antigen monolayers as cellular immunoadsorbents and as plaque indicators. The immunoglobulin nature of the molecule responsible for PFC adherence is suggested by the fact that pretreatment of the PFC with rabbit anti-rat Ig antisera, but not anti-histocompatibility antisera, inhibits adherence. Removal of the adherence capacity of early PFC with the proteolytic enzymes papain and pronase, or by "capping" with anti-Ig is followed by slow regeneration of the ability to adhere, suggesting that adherence is due to membrane rather than secreted immunoglobulin, the latter being detectable within minutes after enzyme treatment. Several time-related events relating to PFC adherence were observed. 1) Both direct and indirect PFC are capable of specific adherence; the ability to adhere, however, tends to decline with time, especially after secondary immunization. 2) Although early PFC adherence is unaffected by trypsin treatment, later populations become increasingly sensitive. 3) Pretreatment of PFC at various times after primary immunization with antisera specific for rat mu-chain indicates that IgM and possibly early IgG-secreting PFC have mu heavy chains on their surface. These data suggest that the PFC membrane is progressively changing during the maturation of the antibody response.
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PMID:Receptors for antigen on lymphoid cells. II. The nature of the molecule responsible for plaque-forming cell adherence. 5 Mar 60

Human properdin (P) was found to be sensitive to the action of trypsin, chymotrypsin, pepsin, and Streptomycetes caesipitosus protease. Incubation of P with these enzymes resulted in loss of its functional activity and the production of antigenically deficient components compared to untreated P. Upon incubation with trypin, P was initially cleaved into a minor fragment and a major fragment. Further degradation ot the fragments occurred with prolongation of inculation time. The minor fragment was highly susceptible to further proteolysis compared to the major fragment which contained the carbohydrate moiety of the molecule. SDS-polyacrylamide gel electrophoretic analysis of trypsin-digested P suggested that the subunit polypeptide chains were initially cleaved at similar points to produce the major and minor fragments. The sedimentation velocity of the major fragment was higher than that of the intact molecule. The implications of these observations of the configuration of P are discussed.
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PMID:Effect of proteolytic digestion on the structure and function of human properdin. 5 3

Supernates derived from in vitro generated T-helper cells have been analyzed for their capacity to substitute for T-cell carrier reactivity. T-helper cell supernates stimulate both a carrier-specific and nonspecific anti-DNP-PFC response to DNP-carrier conjugates in cultures of hapten-primed spleen cells. The carrier-specific and nonspecific activity can be distinguished by dosage optimum, antigen requirements, binding specificity for carrier, and in the requirement for additional splenic adherent accessory cell involvement. The active factors produced in this system are heat labile and sensitive to trypsin and periodate. They are removed by absorption with alloantisera directed toward the strain from which the supernate was derived but not by a variety of anti-immunoglobulin sera.
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PMID:Generation of T-helper cells in vitro. II. Analysis of supernates derived from T-helper cell cultures. 23 20

We have shown that young autoimmune and normal strain mice possess autoantigen-sensitive cells potentially capable of producing anti-sDNA autoantibody in the absence of normal regulatory mechanisms in vitro. In certain strains such as B/W mice, these regulatory mechanisms presumably break down with increasing age, and autoimmunity develops. These regulatory mechanisms might consist of sDNA, T cells, or some combination of these since both of these agents suppressed the anti-sDNA PFC response in vitro. The sDNA may have inhibited PFC development by a receptor blockade mechanism since i) spleen cells pulsed with sDNA for short periods and then washed were suppressed after 5 days of culture; ii) treatment of these blocked cells with trypsin and DNase I restored the anti-sDNA response; iii) the PFC remaining in partially blocked cultures were of lower avidity than PFC in unblocked cultures; and iv) the target of sDNA may be a B cell. Thymocytes and splenic T cells suppressed the anti-sDNA response but not the anti-SRBC response in vitro in a dose-dependent manner. The suppressive capacity of thymus cells did not decline with age in B/W mice. In addition, thymus cells activated by competing foreign antigens could also suppress the anti-sDNA response. The relationship between these modes of regulating autoreactivity remains to be investigated.
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PMID:Regulation of the autoimmune plaque-forming cell response to single-strand DNA (sDNA) in vitro. 35 96

The action of C3bINA and beta 1H on cell-bound C3b is described in this paper. The alpha-polypeptide of C3b that binds covalently to cell surfaces is cleaved by the C3bINA and beta 1H into two fragments: one of 60,000 (C3b alpha-60) and another of 40,000 (C3b alpha-40) daltons. The beta-chain of C3b is unaffected by the C3bINA and beta 1H. The three polypeptides, C3b alpha-60, C3b alpha-40, and C3 beta, are held together as a single unit by disulfide bonds. This unit, referred to as C3b' is covalently bound to cell surfaces via the C3b alpha-60 polypeptide. The conversion of C3b to C3b' by C3bINA and beta 1H abolishes the ability of the C3b-bearing cells to adhere to human erythrocytes as well as the ability to form, on the cell surface, the B, D, and properdin-dependent amplification C3-convertase. However, the agglutinability of the cells with either anti-C3c or anti-C3d is not affected. Treatment of the C3b'-bearing cells with trypsin releases fragments of C3b' into solution, leaving a polypeptide of 32,000 daltons covalently linked to the membrane. Since the trypsinized cells are agglutinable by anti-C3d but not by anti-C3c, the 32,000 dalton polypeptide appears to correspond antigenically to C3d.
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PMID:Action of the C3b-inactivator on the cell-bound C3b. 44 74

Trypsin, a neutral protease, enhanced the direct plaque response of T cell-suffiecient mouse spleen cell cultures to sheep erythrocytes (SRBC) and significantly increased the number of spontaneous PFC against SRBC in cultures without antigen. Moreover, trypsin proved to be able to substitute for T cells in nu/nu spleen cell cultures stimulated with SRBC. Its restorative capacity in this type of response was comparable to the one of lipopolysaccharide. Restoration of antibody synthesis in T cell-deprived cultures could not be explained by enzymatic alteration of SRBC. The data are discussed in terms of a possible role of hydrolytic enzymes released by accessory cells during the induction of an antibody response.
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PMID:Trypsin increases in vitro antibody synthesis and substitutes for helper T cells. 77 82

A highly purified preparation of human properdin (P) has been obtained in a simple two-step procedure utilizing reversed application of the technique of affinity chromatography. The method involved precipitation of properdin from human serum and subsequent passage through an immunoadsorbent column of Sepharose anti-RP globulin which bound the contaminating proteins. The immunochemical properties of the isolated properdin (P) was found to be different from those of activated properdin (P). P was shown to be a 6.1S, beta2 globulin with a mean subunit m.w. of 57,900. P on the other hand was a 5.1S protein with gamma2 mobility and a subunit m.w. of 53,000 daltons. Double diffusion analysis using anti-P revealed a reaction of identity between P and P. However, when the reaction was developed with anti-P, a reaction of partial identity was obtained and the precipitin line of P was seen to spur over the line developed with P. Mild treatment with plasmin or trypsin converted P to P. Unlike P, P was ineffective in triggering the activation of the Properdin System in RP unless trace amounts of zymosan were added. Under these conditions P was found to be converted to P. The results indicate that properdin is present in fresh serum in a precursor form and its activation to P involves a limited proteolytic cleavage of the molecule.
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PMID:Purification of native properdin by reversed affinity chromatography and its activation by proteolytic enzymes. 95 Apr 61

The addition of ovalbumin-immune spleen cells (Ova ISC) to sheep erythrocytes-immune spleen cells (SRBC ISC) in Mishell-Dutton-type cultures resulted in a dramatic reduction of PFC to SRBC and was dependent upon the addition of soluble Ova at low concentrations of Ova ISC. The suppressing cells in the Ova ISC were shown to be irradiation sensitive, depleted by anti-theta antiserum and complement treatment, and did not absorb to glass bead columns. Ova ISC-induced inhibition also occurred in culture chambers across a cell-impermeable membrane and a soluble inhibitor was recovered in chambers opposite the Ova ISC. This suppressor factor was sensitive to trypsin treatment and to heating at 80 degrees C, but not to 70 degrees C, for 30 min. The molecular weight, as determined by sucrose gradient analysis, was between 55,000 and 60,000 daltons. This suppressor factor appears to be distinct from a T-cell "helper" factor which was found to be sensitive to heating at 70 degrees C for 30 min. We propose that this suppressor factor participates in the termination of most immunologic responses and is responsible for the antigenic competition phenomenon.
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PMID:Regulation of the immune response: production of a soluble suppressor by immune spleen cells in vitro. 109 8

The fixation of the third component of complement (C3) results in many important biological phenomenon, among which are (a) immune adherence (1), (b) enhancement of phagocytosis (2,3), (c) the release of an anaphylatoxin which is a potent releaser of histamine (4), and (d) the feedback activation of the alternative pathway (5,6). The physiological mechanisms involving C3 fixation require the generation of a C3 convertase which may occur by two separate pathways. C3 convertase can be generated, in the form of C42, by the so-called classical pathway of activation or in the form C3b,B by the alternative or properdin pathway (7). In both cases, C3 is converted to C3b by cleavage of a small peptide, C3a. Normal human serum contains an inactivator of activated C3b. This C2b inactivator or conglutinogen-activating factor (KAF) has been shown to inhibit both immune hemolysis and the immune adherence properties of C3b and to cause cleavage of C3b in the fixed and fluid- phase stages (8-11). Although it is known that the C3b inactivator is not depleted during its reaction with C3b and that C3b treated with the C3b inactivator becomes extremely sensitive to proteolytic digestion by trypsin and "trypsin-like" enzymes (9), the exact molecular nature of the action of the C3b inactivator on C3b has not been studied. In an effort to delineate the products of this interaction, purified C3b and C3b inactivator were allowed to react for various specific lengths of time and the products of these reactions were then analyzed.
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PMID:The mechanism of action of the C3b inactivator (conglutinogen-activating factor) on its naturally occurring substrate, the major fragment of the third component of complement (C3b). 116 93

Changes in complement levels and protease inhibitors were measured in plasma/serum and peritoneal fluid during 15 attacks of acute pancreatitis. The abnormalities found in the complement system and the protease inhibitors were most pronounced in severe attacks, especially in the peritoneal fluid. Depressed levels of C1q, C3, properdin, and factor I were found in blood on admission in severe attacks. A decrease during the first days of illness was found for C1q, C3, C4, properdin, factor I, and factor H levels in blood. There was a discrepancy between the low C1q and the high C1r and C1s levels in blood. Complexes of C1r-C1s-C1 inactivator and factor B conversion products were found, especially in the peritoneal fluid, denoting an activation of the complement system. High levels of trypsin in complex with alpha 1-protease inhibitor were found, both in blood and in peritoneal fluid, denoting the liberation of active trypsin in acute pancreatitis. The levels of the functional alpha 2-macroglobulin were low, especially in the peritoneal fluid. It is concluded that both classical and alternative complement activation take place in acute pancreatitis, starting in the peritoneal cavity. The magnitude of activation depends on the severity of the disease. Trypsin-induced activation of complement components may explain some of these changes.
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PMID:Correlation among complement activation, protease inhibitors, and clinical course in acute pancreatitis in man. 240 21


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