Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Mouse alpha-macroglobulin and murinoglobulin were labeled with 125I and utilized for plasma clearance studies performed with mice. Desialylated murinoglobulin was rapidly cleared from the circulation with a half-life of about 5 min. On the other hand, desialylated alpha-macroglobulin showed a biphasic curve: about half was cleared at a rate similar to that of the intact molecule while the remaining half had a shorter half-life of about 20 min which was prolonged by a simultaneous injection of a 200-fold excess of unlabeled asialoorosomucoid. Virtually no cross competition was observed between these asialoglobulins and formaldehyde-treated bovine serum albumin or trypsin-bound alpha-macroglobulin. These results suggest that the intravascular elimination of desialylated alpha-macroglobulin and murinoglobulin is independent of the clearance systems responsible for formaldehyde-modified proteins or proteinase-bound alpha-macroglobulins, and that the structure or spatial arrangement, or both, of oligosaccharide units of alpha-macroglobulin is somewhat different from that of murinoglobulin, resulting in a difference of avidity of interaction with the asialoglycoprotein receptor. The desialylated alpha-macroglobulin and murinoglobulin accumulated principally in the liver.
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PMID:Clearance of desialylated mouse alpha-macroglobulin and murinoglobulin in the mouse. 170 51

Alpha-2-Macroglobulin (alpha 2M) is a major plasma proteinase inhibitor. It can also regulate the function of cells of the immune system, including macrophage expression of Ia antigens in tissue culture systems. The present work was done to assess the effect of alpha 2M-trypsin complexes (alpha 2M-t) on macrophage Ia expression in vivo. Bacillus Calmette-Guerin-infected mice were injected intraperitoneally with 100nM alpha 2M-t, phosphate buffered saline (PBS), or bovine serum albumin (BSA) in PBS. The peritoneal cells were harvested by lavage from 3 to 6 days after injection. Differential cell counts were performed, and macrophage Ia antigen expression determined by indirect immunofluorescence. Injection of either alpha 2M-t or BSA solutions tended to increase the number of total cells and lymphocytes harvested, without changing the number of macrophages harvested. alpha 2M-t injection reduced the proportion of macrophages which were Ia positive from 60 to 37% on day 3 after injection, and to 20% Ia positive on day 6. The reduction in Ia positive macrophages was statistically significant when compared to either PBS or BSA injected groups. In summary, in vivo exposure to alpha 2M-t can alter macrophage function. alpha 2M-proteinase complexes formed during the course of coagulation or inflammation may play a physiologic role as regulators of the immune response.
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PMID:The effect of alpha 2 macroglobulin-proteinase complexes on macrophage Ia expression in vivo. 171 9

We looked for the presence of prorenin in erythrocytes from normal subjects (n = 8), hypertensive patients (n = 8), and pregnant women (n = 8). Angiotensin I generation was measured at 37 degrees C, pH 5.7, in the presence of homologous substrate (1400 ng/mL) before and after trypsin activation (100 micrograms/mL) in (A) haemolyzed erythrocytes, (B) supernatants of haemolyzed erythrocytes, and (C) in the sixth washing of erythrocytes diluted 1:1 with a 0.1 M Tris buffer containing 0.5% bovine serum albumin and protease inhibitors. Haemolyzed erythrocytes generated angiotensin I only after trypsin treatment, and the rate of generation was the same (A) before and (B) after centrifugation at 20,000g, indicating the absence of prorenin bound to the cell membranes. When aliquots of the last washing of erythrocytes (C) were tested for angiotensin I generation before and after trypsin, they did not generate angiotensin I, indicating that residual prorenin from the plasma was no longer present in our preparation. Angiotensin I generation by trypsin-treated A and B was completely abolished by preincubation with anti-renin serum. The level of prorenin was not significantly different in the erythrocytes from normal, hypertensive, and pregnant subjects (68 +/- 10, 58 +/- 7 and 107 +/- 17 pg angiotensin I.mL-1.h-1, ns) in spite of their very different plasma levels (21 +/- 2.5, 17 +/- 2.4 and 110 +/- 12 ng angiotensin I.mL-1.h-1, p less than 0.01 for pregnant women compared with both normal and hypertensive subjects). Our data show that prorenin is present in human erythrocytes in fairly constant and clearly detectable amounts, thus suggesting a possible intracellular role for it.
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PMID:Prorenin is present in human red blood cells. 175 45

A variety of nonhistone proteins and polyamines has been studied for their substrate activity for nuclear histone N-acetyltransferase. Nonhistone chromatin high-mobility group (HMG) proteins are found to be as good a substrate for the enzyme as histones. The enzyme also acetylates spermidine and spermine. However, protamine, bovine serum albumin, and ubiquitin are not substrates. Chymotryptic peptides of histone and HMGs retained about 64% of the substrate activity, but trypsin treatment reduced the substrate activity by more than 85%. Both N-acetyltransferase activities for HMGs and histones are copurified through salt extraction, polyethylene glycol fractionation, and chromatography on DEAE-cellulose, phosphocellulose columns, and a HPLC anionic-exchange column. The highly purified nuclear histone acetyltransferase shows similar optimal pH and ping-pong kinetics for both HMGs and histones. The Km for HMG is 0.25 mg/ml. HMGs are able to accept the acetyl group from isolated acetyl-enzyme intermediate. Denatured gel analysis shows that HMG 1 and HMG 2 are the major proteins acetylated. High salt concentrations, mononucleotides, and DNA, which inhibit histone substrate activity of the enzyme, also inhibit HMG substrate activity. These observations suggest that there is a major nuclear N-acetyltransferase which is responsible for the acetylation of both histones and HMGs and perhaps also of spermine and spermidine. Thus the regulation of the structure and function of chromatin through postsynthetic acetylation can be achieved by a single nuclear N-acetyltransferase.
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PMID:High-mobility group and other nonhistone substrates for nuclear histone N-acetyltransferase. 177 1

The nonenzymic glucation of most proteins occurs only at epsilon-amino groups of lysine residues. Hydrolysis catalyzed by bovine trypsin, porcine trypsin and pineapple bromelian were studied using native and glucated proteins as substrates. Glucosylated ovalbumin, human serum albumin, gamma-globulin and myoglobin show reduced susceptibility to degradation by trypsin as compared to the nonglucated proteins, apparently by direct modification of lysine residues. Trypsin cleaves at substrate arginine and lysine peptides bonds. Bromelian, a less specific enzyme, shows similar hydrolysis rates for native casein, ovalbumin and myoglobin, and identical rates for glucated hemoglobin and myoglobin. Bovine trypsin showed 100% decrease in enzymatic activity with glucated human serum albumin and gamma-globulin and pineapple bromelian with human serum albumin.
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PMID:[Effect of non-enzymic glycosylation on reactivity in proteolysis]. 184 56

Ejaculated spermatozoa from brush-tailed possums and tammar wallabies were washed by a 'swim up' procedure into Hanks Balanced Salt Solution (HBSS), and then exposed to test solutions. Spermatozoa were incubated at 33 degrees C, or room temperature when long-term sperm survival (greater than 10 h) was required. Exposure of spermatozoa to calcium ionophore A23187, cyclic nucleotides, phosphoinositide pathway intermediates, lysophospholipids, trypsin or 'capacitating' high ionic-strength medium (380 mosmol) followed by 3% bovine serum albumin for periods up to 24 h did not induce acrosomal loss. However, there were major changes within the acrosome: large numbers of empty membrane-bound vesicles were formed, the electron density of the acrosomal matrix decreased and the acrosome swelled slightly. The origin of the vesicles is unclear but the acrosomal membranes and the plasma membrane remained intact.
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PMID:Stability of the acrosome of the brush-tailed possum (Trichosurus vulpecula) and tammar wallaby (Macropus eugenii) in vitro and after exposure to conditions and agents known to cause capacitation or acrosome reaction of eutherian spermatozoa. 184 24

The biological and physical properties of albumin and nitroxides make them attractive candidates as special purpose MRI contrast agents which could be used to study the intravascular compartment or specific targets in tissues. In this study, albumin-nitroxide complexes were prepared by reduction and alkylation of the disulfide bonds of the protein and characterized by electron spin resonance and ultraviolet absorption spectroscopy. An average of six nitroxides were bound covalently to each molecule of human serum albumin. The water proton relaxivity of the protein-bound nitroxide (at 20 MHz and 37 degrees C) was 4-fold greater than that of the free nitroxide. The digestion of the nitroxide-albumin complexes by cells or by trypsin decreased the relaxivity of the nitroxide-protein complex. The rate of reduction of albumin-bound nitroxide by cells was much slower than that of the free nitroxide but still was oxygen-sensitive (2-3-fold increase in the rate of reduction in the absence of oxygen).
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PMID:Potential of albumin labeled with nitroxides as a contrast agent for magnetic resonance imaging and spectroscopy. 196 24

Recent studies from this laboratory have demonstrated the presence of thyroid hormone response elements (TREs) in the 5'-flanking region of the rat alpha and TSH beta subunit genes. Using an avidin-biotin complex DNA binding assay, we have shown that these TREs bind the thyroid hormone (T3) receptor present in nuclear extracts of GH3 cells, as well as the in vitro synthesized Hc-erbA beta, which has been identified as a member of the family of T3 receptors. The binding of Hc-erbA beta to the alpha subunit TRE can be enhanced 3-4-fold by including GH3 nuclear extract in the binding assay. Binding to the TRE present in the TSH beta gene or the rat growth hormone gene was similarly enhanced, although to a lesser degree. The enhanced binding activity is trypsin-sensitive and heat labile, and is not reproduced by the addition of histones, bovine serum albumin, or cytosol instead of nuclear extract. Gel exclusion chromatography suggests a molecular size of approximately 65,000 Da. This protein, which is present in several different cell types, is also able to complement binding of the rat erbA alpha-1 and the pituitary-specific erbA beta-2 forms of the receptor. These data suggest that the binding of the T3 receptor to a TRE is augmented by another nuclear protein, which may be involved in the mechanism of action of thyroid hormone.
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PMID:A nuclear factor that enhances binding of thyroid hormone receptors to thyroid hormone response elements. 196 58

Plasma membranes were isolated from A431 cells previously labelled with myo-[3H]inositol during exponential growth, using a rapid procedure on Percoll gradients. They displayed a significant phospholipase (PLC) activity against phosphoinositides, which was stimulated by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), epidermal growth factor (EGF) and fetal calf serum (FCS) (24%, 11% and 97% over controls, respectively). The effect of EGF was not significantly increased by GTP gamma S. Upon addition of cytosol, EGF promoted an almost 100% stimulation of inositol 1,4,5-trisphosphate and inositol bisphosphate generation, which displayed an absolute requirement for GTP gamma S. This dose-dependent effect of cytosol was linear until 60 micrograms/ml of cytosolic protein and decreased afterwards; it was abolished by heat treatment and trypsin hydrolysis, and it was not reproduced by an identical amount of bovine serum albumin. The same biphasic stimulation was observed with phosphotyrosyl proteins immunopurified from cytosol of A431 cells previously stimulated by EGF. Since phosphotyrosyl proteins displayed PLC activity, our data suggest that soluble protein substrates of EGF receptor tyrosine kinase, including PLC, could be involved in the regulation of phosphoinositide hydrolysis in response to EGF. Using phosphatidyl[3H]inositol 4,5-bisphosphate (PIP2) dispersed with unlabelled phosphatidylethanolamine and phosphatidylserine as an exogenous substrate, no stimulation of PLC activity by EGF could be detected, either with membranes or with membranes plus cytosol. It is concluded that EGF might stimulate hydrolysis of phosphoinositides by PLC through complex interactions between plasma membrane and cytosolic factors which still remain to be identified.
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PMID:Stimulation by epidermal growth factor of inositol phosphate production in plasma membranes from A431 cells. 198 83

C-reactive protein (CRP) is an acute phase inflammatory protein in man which binds to phosphocholine, chromatin, histones, and the 70-kDa protein of the U1 small nuclear ribonucleoprotein particle in a calcium-dependent, phosphocholine-inhibitable manner. CRP also binds to other proteins including fibronectin. The determinants involved in CRP binding to these diverse proteins have not been identified. The binding of CRP to histones was examined as these proteins are available in large quantity at high purity and subject to protease digestion with well characterized products. Histone H1 was digested with thrombin and trypsin to produce three distinct fragments, N-terminal, central globular, and C-terminal. CRP was shown only to bind to the C-terminal fragment. Binding to histone H2A was also examined. CRP binding was not diminished by cleavage of the C-terminal fragment but was greatly decreased when the central globular region of H2A was tested. Peptides were prepared to be identical to the N- and C-terminal fragments of H2A. The N-terminal (15 amino acid) fragment of H2A blocked CRP-induced precipitation of phosphocholine-coupled bovine serum albumin and histone H2A, whereas the C-terminal fragment showed no inhibition. Thus we have defined the first reported CRP binding determinant on a protein.
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PMID:Definition of a C-reactive protein binding determinant on histones. 198 77


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