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)

Trypsin treatment of intact cells or isolated plasmalemmae from embryonic chick neural retinae leads to an accumulation of lysophospholipids in the plasmalemmae. Trypsin was used at activities commonly used in cell disaggregation techniques. This accumulation appears to result from the decrease in acyltransferase activity in the plasmalemma produced by enzyme treatment. Plasmalemmal CoA ligase activity is not affected by trypsin treatment. Trypsinization has little effect on plasmalemmal phospholipase A2 activity. These results are discussed in relation to (a) the effects of trypsinization on cell adhesion, and (b) the theory that cells cannot adhere to lecithins because of their fluidity or surface-free-energy values. We propose that the effects of trypsinization on adhesion may in large part be due to the effects on other plasmalemmal proteins. Similarly the inability of cells to adhere to lecithin substrates is simply explained as being due to the lysolecithin that contacting cells release from these substrates.
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PMID:Cell surface lipids and adhesion. IV. The effects of trypsin on lipid turnover by the plasmalemma. 52 67

Ehrlich ascites tumor cells spontaneously release cell surface material (glycocalyx) into isotonic saline medium. Exposure of these cells to tritium-labeled 4,4'-diisothiocyano-1,2-diphenylethane-2,2'-disulfonic acid (3H2DIDS) at 4 degrees C leads to preferential labeling of the cell surface coat. We have combined studies of the kinetics of 3H2DIDS-label release, the effects of enzymatic treatment, and cell electrophoretic mobility to characterize the 3H2DIDS-labeled components of the cell surface. Approximately 73% of the cell-associated radioactivity is spontaneously released from the cells after 5 h at 23 degrees C. The kinetics of release is consistent with the first-order loss of two fractions; a slow (tau 1/2 = 360 min) component representing 33% of the radioactivity and a fast (tau 1/2 = 20 min) component representing 26%. The remaining 14% of the labile binding may reflect mechanically induced surface release. Trypsin (1 microgram/ml) also removes approximately 73% of the labeled material within 30 min and converts the kinetics of release to that of a single component (tau 1/2 = 5.5 min). The specific activity (SA) of material released by trypsin immediately after labeling is 83% of the SA of the material spontaneously lost in 1 h. However, trypsinization following a 2-h period of spontaneous release yields material of reduced (43%) SA. Neither 3H2DIDS labeling nor the initial spontaneous loss of labeled material alters cell electrophoretic mobility. However, extended spontaneous release is accompanied by a significant decrease in surface charge density. Trypsinization immediately following labeling or after spontaneous release (2 h) reduces mobility by 32%. We have tentatively identified the slowly released compartment as contributing to cell surface negativity.
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PMID:Ehrlich ascites tumor cell surface labeling and kinetics of glycocalyx release. 54 32

Trypsin immobilised on polystyrene beads causes initiation of cell division which cannot be accounted for by trypsin released into the medium or into the cells. Also, initiation by soluble trypsin is inhibited by immobilised soybean trypsin inhibitor. These results demonstrate that trypsin can initiate proliferation at the cell surface.
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PMID:Initiation of check cell division by trypsin action at the cell surface. 56 13

Trypsin-catalyzed syntheses of peptides were performed using various N-acylated amino acid or peptide esters as donors and amino acid derivatives, peptides, or their derivatives as acceptors. The synthesis was almost quantitative under optimal conditions. Considerably more enzyme and a more alkaline pH were necessary for synthesis than hydrolysis. Another very important condition was the concentration of the starting materials; higher concentrations resulted in much better product yields. The nucleophile specificity for synthesis was also important; hydrophobic or bulky amino acid residues were most efficient at the P1' position, and L-proline as well as D-amino acid residues were the worst choices. The synthesis was also dependent on the solubility of the products synthesized; the yield was higher with products of lower solubility. As donor esters, good substrates were all useful. Accordingly, fragment condensation was possible using N-acylated peptide esters and various peptides. The present study suggests that trypsin may become a useful tool for peptide synthesis.
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PMID:Trypsin as a catalyst for peptide synthesis. 56 76

Loss of maturation features is demonstrated for 8-day-old chick embryo heart myocytes, once they have been completely dissociated by trypsin. In support of this statement a total of 65 sections of six isolated cells, fixed while still spherical or during early flattening, were examined under the electron microscope. Trypsin-separated heart muscle cells, even though originating from already differentiated embryonic heart tissue, can therefore in principle be used for differentiation experiments in culture. However, the same cell suspensions also yielded an appreciable quantity of nonisolated cells. In such cell complexes, one can find areas showing well-ordered fibrils and intercalated disks. From 27 sections of a cell pair incidentally transferred into culture undissociated and then fixed while still in the globular state, the fourth and fifth sections, starting from the substrate side of the culture, showed an intercalated disk. Because of its small diameter, this cell complex would hardly have been retainable by a gauze with meshes likely to allow passage of only single cells. Thus the availability of differentiation experiments in culture, starting with already differentiated heart tissue, is restricted to cases where, in a selected territory, each cell has been established without doubt as isolated.
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PMID:Loss of differentiation features in trypsin separated heart muscle cells. 56 47

Treatment of chromatin subunits (nucleosome monomers) with formaldehyde results in the formation of cross-links between DNA and histones and between histones and histones. Digestion of chromosomal proteins with proteinase K does not lower the protein/DNA weight ratio below 0.08 to 0.1 as determined by cesium chloride gradient centrifugation of the digestion product from formaldehyde-treated nucleosomes. In addition to proteinase K, formaldehyde-treated nucleosomes were tested for accessibility to trypsin and pronase. The CsCl gradient patterns show, that pronase digestion and proteinase K treatment yield similar results. Trypsin treatment of control and formaldehyde-treated nucleosomes shows, that the sites which are accessible for trypsin in native nucleosomes, are blocked after formaldehyde treatment. Analysis of the CsCl gradient peak fractions in polyacrylamide gels shows, that the reliability of DNA fragment size determinations depends on the completeness of deproteinization.
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PMID:Digestion of chromosomal proteins in formaldehyde treated chromatin. 56 16

Trypsin, chymotrypsin and elastase are the pancreatic enzymes required for neonatal rat heart tissue disaggregation. We have previously developed a procedure for the isolation of a mixture of these three enzymes from commercial crude-trypsin samples. Toxic materials present in certain crude-trypsin samples are removed during purification. An evaluation of this mixture was conducted for its ability to disaggregate neonatal rat heart tissue for cell culture. Large numbers of cells were released with minimal cellular damage as determined by their ability to survive and function in culture. Rat lung and kidney tissue also were disaggregated successfully and cultured with this preparation. It is apparent that this enzyme preparation has a potential for disaggregating a wide variety of tissues.
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PMID:Evaluation of a proteolytic enzyme mixture isolated from crude trypsins in tissue disaggregation. 56 19

Footpad adhesion sites pinch off from the rest of the cell surface during EGTA-mediated detachment of normal or virus-transformed murine cells from their tissue culture substrates. In these studies, highly purified trypsin and testicullar hyaluronidase were used to investigate the selective destruction or solubilization of proteins and polysaccharides in this substrate-attached material (SAM). Trypsin-mediated detachment of cells or trypsinization of SAM after EGTA-mediated detachment of cells resulted in the following changes in SAM composition: (a) solubilization of 50-70% of the glycosaminoglycan polysaccharide with loss of only a small fraction of the protein, (b) selective loss of one species of glycosaminoglycan-associated protein in longterm radiolabeled preparations, (c) no selective loss of the LETS glycoprotein or cytoskeletal proteins in longterm radiolabeled preparations, and (d) selective loss of one species of glycosaminoglycan-associated protein, a protion of the LETS glycoprotein, and proteins Cd (mol wt 47,000 and Ce' (mol wt 39,000) in short term radiolabeled preparations. Digestion of SAM with testicular hyaluronidase resulted in: (a) almost complete solubilization of the hyaluronate and chondroitin sulfate moieties from long term radiolabeled SAM with minimal loss of heparan sulfate, (b) solubilization of a small portion of the LETS glycoprotein and the cytoskeletal proteins from longterm radiolabeled SAM, (c) resistance to solubilization of protein and polysaccharide in reattaching cell SAM which contains principally heparan sulfate, and (d) complete solubilization of the LETS glycoprotein in short term radiolabeled preparations with no loss of cytoskeletal proteins. Thus, there appear to be two distinct pools of LETS in SAM, one associated in some unknown fashion with hyaluronate-chondroitin sulfate complexes, and a second associated with some other component in SAM, perhaps heparan sulfate. These data, together with other results, suggest that the cell-substrate adhesion process may be mediated principally by a heparan sulfate--LETS complex and that hyaluronate-chondroitin sulfate complexes may be important in the detachability of cells from the serum-coated substrate by destabilizing LETS matrices at posterior footpad adhesion sites.
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PMID:Two functionally distinct pools of glycosaminoglycan in the substrate adhesion site of murine cells. 56 61

Normal adult C57BL/6J fibroblasts, cultured to saturation density and therefore in resting phase, were harvested by EDTA, treated with trypsin at various concentrations for different lengths of time and then tested for absorbing capacity of a C57BL/He anti-embryo serum, the residual cytotoxic activity being measured by a 51Cr release assay on a C57BL/He lymphosarcoma known to carry embryonic antigens. A weak proteolytic treatment (0.05-0.25% trypsin for 5-10 min) uncovered structures which absorbed over 40% activity of the anti-embryo serum. The treated fibroblasts partially retained the absorbing capacity for an antihistocompatibility serum. Higher doses or longer exposure to trypsin progressively inactivated the absorbing capacity of fibroblasts for both antisera. Trypsin treatment of fibrosarcoma cells, which when untreated completely absorbed the anti-embryo serum, decreased their absorbing capacity. Additionally, normal untreated fibroblasts in growing phase were found to absorb the anti-embryo serum.
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PMID:Onco-embryonic antigens on murine normal adult cells. 57 65

We have studied in vitro the interaction of peritoneal macrophages with 'old' and 'young' RBC, as well as with enzymatically treated 'old' and 'young' RBC from syngeneic mice. 'Old' RBC were recognized and phagocytized by macrophages, whereas 'young' RBC were not. Neuraminidase treatment of both 'young' and 'old' RBC had little effect on the extent of phagocytosis. Trypsin treatment, on the other hand, markedly reduced the phagocytosis of 'old' RBC and had no effect on the phagocytosis of 'young' RBC. The level of phagocytosis of 'old' RBC by macrophages from mineral-oil treated mouse peritoneal cavities was roughly half that of macrophages from untreated mice. It is postualted that 'old' RBC could be recognized due to the presence of cytophilic antibodies on the surface of the macrophages. The specificity of these hypothetical cytophilic antibodies is believed to be directed towards sites which are absent or shielded in 'young' RBC, and exposed in 'old' RBC. Trypsin treatment of 'old' RBC appears to remove these antigenic sites from the 'old' RBC. The lower level of phagocytosis of 'old' RBC by mineral-oil induced macrophages could be due to the previous phagocytic activity of these cells, and their relatively uncoated, newly form plasma membrane, lacking cytophilic antibodies. In support of this hypothesis, we have demonstrated that trypsin treatment of macrophages resulted in a markedly decreased phagocytosis of 'old' RBC.
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PMID:Phagocytosis of 'old' red blood cells by macrophages from syngeneic mice in vitro. 59 Apr 5


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