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)

The susceptibility of lactoferrin in bovine colostrum and human milk to digestion by trypsin and chymotrypsin has been investigated. Neither enzyme had much effect on the lactoferrin-mediated antimicrobial activity of human milk, and the iron binding capacity of lactoferrin in the milk was only slightly reduced. Likewise both enzymes had only a slight effect on the iron-binding capacity of purified lactoferrin. Although iron-free (apo)lactoferrin was slightly more susceptible to digestion, especially by chymotrypsin, than the iron-saturated form, the difference was much less than has been found in earlier studies with other proteins of the transferrin class. In contrast, trypsin destroyed the antimicrobial activity of bovine colostrum, and, in line with earlier studies, appreciably reduced the iron-binding capacity of both colostrum and purified bovine apolactoferrin. Bovine iron-saturated lactoferrin was more resistant to digestion. The unusual resistance of human apolactoferrin to proteolysis may reflect an evolutionary development designed to permit its survival in the gut of the infant.
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PMID:The effect of trypsin and chymotrypsin on the in vitro antimicrobial and iron-binding properties of lactoferrin in human milk and bovine colostrum. Unusual resistance of human apolactoferrin to proteolytic digestion. 634 99

Primary mixed cultures of trypsin-dissociated fetal and newborn rat brain and spinal cord have been grown in a serum-free medium. This medium, containing insulin, selenium, transferrin and triiodothyronine, was optimized for oligodendrocyte survival by determining the number of cells which expressed surface galactocerebroside. Comparison of cultures in serum-containing and serum-free media revealed that galactocerebroside positive (GalC+) oligodendrocytes could be detected earlier in the absence of serum. This early differentiation occurred in the absence of the added hormones and nutrients, whose main function appeared to be to prolong survival of the cells. The effect of serum on the differentiation of oligodendrocytes was studied by comparing the expression of surface GalC in media containing 2.5% or 10% fetal calf serum. At a given time a much greater number of GalC+ oligodendrocytes could be detected at the lower serum concentration. However, when cultures were transferred from 10% serum to serum-free medium (or 1% serum) large numbers of GalC+ oligodendrocytes subsequently appeared, showing that precursors were present in the high-serum medium, but that they were unable to differentiate. Possible explanations of the effect of serum on oligodendrocyte differentiation are discussed.
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PMID:The differentiation of oligodendrocytes in a serum-free hormone-supplemented medium. 638 6

Epithelial cells filled with lymphocytes (nurse cells, NC), recently described in mouse, rat and human thymus, have been interpreted as mediators of direct contact ('stromal') induced thymocyte maturation. We describe analogous NC in trypsin-dissociated human adenoids and tonsils. NC from these organs show morphological characteristics analogous to those of thymic NC: they appear as large (diameter 30-35 micrometers) elements, containing peripherally situated tonofilament bundles, electrodense mitochondria and some vacuoles. Each NC contains 5-30 intact lymphoid cells, some of which appear in the activated state. NC show neither phagocytic ability, nor ANAE and peroxidase cytochemical reactions. The majority of NC from adenoids and tonsils react with the monoclonal antibody (McAb) OKIa1 (DR w framework) as those from thymus, and 40% of them bind fluorescein-conjugated peanut agglutinin. Some of them also react with the McAb OKT3 (pan-T), OKT9 (transferrin receptors) and OKT10 (immature hematopoietic cells). The presence of NC in adenoids and tonsils suggests that these organs may be involved in some stages of lymphocyte maturation requiring intimate contact with epithelial cells.
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PMID:Epithelial-like cells containing lymphocytes (nurse cells) in human adenoids and tonsils. 652 55

An established cell line (TM-4) derived from murine Sertoli cells, the major supportive cell type of the testes, secretes a protein that binds retinol when grown in serum-free chemically defined medium. The protein that binds retinol is trypsin-sensitive and has an apparent Kd for retinol of 54 nM. Cholesterol, retinyl acetate, or UV-irradiated retinol at levels 100-fold in excess of retinol are poor competitors of [3H]retinol binding. Retinoic acid at a 100-fold molar excess inhibited [3H]retinol binding by 71%. In contrast, excess unlabeled retinol completely inhibits [3H]retinol binding. More than 80% of the total retinol-binding activity in confluent cultures is found in the culture medium. Prior to incubation with retinol, the protein that binds retinol has an apparent Mr of less than 150,000 by column chromatography; however, after incubation with retinol the protein that binds retinol exhibits an apparent Mr of 2 X 10(6) or greater and a sedimentation coefficient greater than 4 S. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals that the major iodinatable component of the aggregated protein that binds retinol has an apparent Mr of 70,000. The secreted protein that binds retinol is not immunologically cross-reactive with either serum or cellular retinol-binding protein or transferrin. These findings suggest that Sertoli cells may secrete a protein that binds retinol. Such a protein could be involved in the transport of retinol either to the lumen of the seminiferous tubules or to the developing germ cells themselves.
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PMID:Synthesis and secretion of a novel binding protein for retinol by a cell line derived from Sertoli cells. 653 97

The accumulation of mast cells is characteristic of a number of pathological states. We demonstrate here the directional motility of mast cells in vitro in response to tumor-derived peptides. Rat peritoneal mast cells were isolated on Percoll gradients and maintained in serum-free medium containing transferrin, albumin, soybean lipid, and cholesterol. The isolated mast cells migrated under agarose in response to medium conditioned by any of eight tumor cell lines but not to medium conditioned by any of a variety of nontumorigenic cell types. The tumor-derived activity is dialyzable (cutoff, Mr 3500), stable to trypsin treatment and to heating at 56 degrees, but destroyed by heating to 100 degrees or by treatment with Streptomyces griseus protease or carboxypeptidase A. Ultrafiltration suggests a molecular weight of 300 to 1000. Two tripeptides, glycylhistidyllysine and N-formylmethionylleucylphenylalanine, were also found to be potent chemoattractants for mast cells. N-Formylmethionylphenylalanine and valylglycylserylglutamic acid (eosinophil chemotactic Factor A) had significantly less chemoattractant activity over the same range of concentrations. Several peptide analogues of glycylhistidyllysine were tested and found to have no activity. The growth of capillary blood vessels toward a growing tumor is generally preceded by an accumulation of mast cells at the tumor site. Based on the results presented here and previous data from our laboratory on mast cell stimulation of capillary endothelial cell migration, we propose an hypothesis that the chemoattraction of mast cells by tumor-derived peptides may be an important early event in tumor neovascularization.
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PMID:Stimulation of rat peritoneal mast cell migration by tumor-derived peptides. 664 May 37

Mild treatment of iron-saturated human lactotransferrin by trypsin at pH 8.2 cleaves the molecule into a N-tryptic (Mr approximately equal to 30000) and a C-tryptic (Mr approximately equal to 50000) fragment, which have been isolated. Each of them carries a glycan moiety and keeps the property to bind reversibly one Fe3+. The N-tryptic fragment has been submitted to a second tryptic digestion which led to an iron-binding glycopeptide fragment with a molecular weight of about 18500. This fragment, the smallest iron-binding peptide isolated up to now from a transferrin, includes the ND2 domain of human lactotransferrin.
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PMID:Characterization and localization of an iron-binding 18-kDa glycopeptide isolated from the N-terminal half of human lactotransferrin. 672 76

An improved Ham's F12 nutrient medium supplemented with epidermal growth factor (EGF), insulin (INS), and transferrin (TF) was developed for continuous proliferation and clonal growth of primary rabbit tracheal epithelial (TE) cells in culture. The addition of small quantities of fetal bovine serum (FBS) (0.01 to 0.1%) to cultures had little measureable stimulation on TE cell growth and plating efficiency. However, serum levels higher than 0.1% inhibited cell growth and also masked the growth stimulating activities of EGF and INS despite an increase in cell attachment. Under this defined, hormone-supplemented medium, and in the presence of a trace amount of serum (0.01%), 10 to 20% of the protease-dissociated TE cells attached to the culture dish followed by at least four population doublings during 7 to 10 d of culture. Clonal growth occurred at a seeding density of 17 cells/cm2 with a plating efficiency of 6 to 8%. Confluent primary cultures could be passaged two to four times by treatment with a 0.1% trypsin-1 mM EDTA solution and a total of 10 to 30 population doublings of in vitro life span were obtained. The epithelial nature of cultured cells was confirmed by indirect immunofluorescent staining with antikeratin antibody as well as by transmission electron microscopy. This study shows that using this improved hormone-supplemented medium, rabbit TE cells can be maintained in culture for extended periods of time without the aid of a fibroblast feeder layer or explant tissue. This system could be useful for the study of cell differentiation of tracheal epithelium.
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PMID:Continuous multiplication of rabbit tracheal epithelial cells in a defined, hormone-supplemented medium. 675 9

UDP-galactose: N-acetylglucosamine galactosyltransferase (GT) and CMP-sialic:desialylated transferrin sialyltransferse (ST) activities of rat liver Golgi apparatus are membrane-bound enzymes that can be released by treatment with Triton X-100. When protein substrates are used to assay these enzymes in freshly prepared Golgi vesicles, both activities are enhanced about eightfold by the addition of Triton X-100. When small molecular weight substrates are used, however, both activities are only enhanced about twofold by the addition of detergent. The enzymes remain inaccessible to large protein substrates even after freezing and storage of the Golgi preparation for 2 mo in liquid nitrogen. Accessibility to small molecular and weight substrates increases significantly after such storage. GT and ST activities in Golgi vesicles are not destroyed by treatment with trypsin, but are destroyed by this treatment if the vesicles are first disrupted with Triton X-100. Treatment of Golgi vesicles with low levels of filipin, a polyene antibiotic known to complex with cholesterol in biological membranes, also results in enhanced trypsin susceptibility of both glycosyltransferases. Maximum destruction of the glycosyltransferase activities by trypsin is obtained at filipin to total cholesterol weight ratios of approximately 1.6 or molar ratios of approximately 1. This level of filipin does not solubilize the enzymes but causes both puckering of Golgi membranes visible by electron microscopy and disruption of the Golgi vesicles as measured by release of serum albumin. When isolated Golgi apparatus is fixed with glutaraldehyde to maintain the three-dimensional orientation of cisternae and secretory vesicles, and then treated with filipin, cisternal membranes on both cis and trans faces of the apparatus as well as secretory granule membranes appear to be affected about equally. These results indicate that liver Golgi vesicles as isolated are largely oriented with GT and ST on the luminal side of the membranes, which corresponds to the cisternal compartment of the Golgi apparatus in the hepatocyte. Cholesterol is an integral part of the membrane of the Golgi apparatus and its distribution throughout the apparatus is similar to that of both transferases.
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PMID:Orientation of glycoprotein galactosyltransferase and sialyltransferase enzymes in vesicles derived from rat liver Golgi apparatus. 678 76

Iron-saturated bovine transferrins A, D1, D2 and E were cleaved by trypsin yielding monoferric fragments. The N-terminal fragments (F) of transferrins A and D2 had identical mobility in cellulose acetate electrophoresis, that of transferrin D1 a slower mobility, and that of E a still slower mobility. The C-terminal fragments (S) gave multiple bands which were essentially identical in the case of transferrins A, D1, and E, but of slower mobility in the case of transferrin D2. All four variants had identical N-terminal amino acid sequences. The electrophoretic mobility of the C-terminal fragments was reduced by neuraminidase treatment, but the N-terminal fragments were unaffected. The four transferrin variants therefore appear to be made up from three electrophoretically distinguishable N-terminal halves and two C-terminal halves. The feature responsible for the electrophoretic double banding of homozygous bovine asialotransferrins is consistently associated with the C-terminal half of the molecule.
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PMID:Electrophoretic mobility of N- and C-terminal monoferric fragments of bovine transferrin phenotypes AA, D1D1, D2D2, and EE, and N-terminal amino acid sequences. 722 82

Erythrocyte deformability, whole blood viscosity, hematocrit, as well as fibrinogen and plasminogen concentrations were checked in 39 clinically intact women of whom 22 had been on (OCs) oral contraceptives for up to 5 years. Also determined were several serum proteins, such as transferrin, coeruloplasmin, alpha-2 macroglobulin, alpha-1 trypsin, beta-lipoprotein, and inactivated complement C3. 17 women with IUDs were chosen to form a control group. Proteins with sensitivity to estrogen as well as whole blood viscosity were found to be increased, whereas erythrocyte deformability was decreased. Yet, no hemodynamic manifestation took place of those rheological parameters, since hematocrit declined or remained constant, and no change occurred to fibrinogen and plasminogen concentrations. (author's)
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PMID:[Flow properties of blood in women on oral contraceptives (author's transl)]. 728 69


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