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 response of human colon adenocarcinoma cells of the line WiDr to the combined treatment of ionizing radiation and photosensitization by 5-aminolevulinic acid-induced protoporphyrin IX was assessed by a colony-forming assay. A dose of X rays inactivating approximately 50% of the cells was used. Seventy to 85% of the cells accumulated in S and G2 + M phase 12-24 h after such a treatment as measured by flow cytometry, while the distribution of cells in the phases of the cell cycle approached that of untreated cells 48 h after X-ray treatment. Cellular photosensitization was developed by endogenous synthesis of protoporphyrin IX (PPIX) from the precursor 5-aminolevulinic acid (5-ALA). This was performed by treating the cells with 1 mM 5-ALA for 4 h in a serum-free medium. The endogenous synthesis of PPIX increased with time after the cells had been subcultured, i.e. the ability of the cells to synthesize PPIX increased 1.5-2-fold within 48 h of incubation. This was not due to effects of trypsin on the cells. Photochemotherapy with 5-ALA was given 0-48 h after X rays. The combined cytotoxic effect was analyzed by an isobologram after correction of the survival curves for microcolony formation and differences in intracellular concentration of PPIX. The results indicate that 5-ALA PCT given 0-4 h after X rays acts slightly antagonistically while 5-ALA PCT given 12-48 h after X rays acts slightly synergistically.
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PMID:Combined treatment of ionizing radiation and photosensitization by 5-aminolevulinic acid-induced protoporphyrin IX. 776 84

Sodium oleate cosolubilized with lysozyme in reverse micellar solutions is shown to inhibit the ozone-mediated oxidation of tryptophan residues in the protein. The magnitude of inhibition by oleate, which is an indirect measure of the fraction of ozone that reacts with oleate instead of the protein, is predictable using a kinetic model that is based on the concentrations and the reactivities toward ozone of the amino acid residues in lysozyme and the double bond in oleate. Oleate (2 mM), linoleate (1 mM), linolenate (0.67 mM), and gamma-linolenate (0.67 mM) all inhibit the ozonation of lysozyme similarly; this indicates that ozone reacts with double bonds in mono-, di-, or polyunsaturated fatty acids at approximately the same rate. All these fatty acids reside at the micellar interface with their head groups facing inward toward the dispersed water pools and the hydrocarbon tails projecting into the bulk, continuous organic phase. Various short-chain 2-, 3-, and 4-alkenoic acids that reside predominantly in the water pools, and long-chain alkenes that reside in the bulk organic solvent, have a similar inhibitory effect on the ozone-mediated oxidation of tryptophan residues in lysozyme. Thus, the location of olefinic compounds in the micelles or bulk organic phase per se does not influence the rate of reaction in this reverse micellar system. A number of proteins that reside in the water pools of reverse micelles are found to behave similarly to lysozyme, including albumin, carbonic anhydrase, beta-casein, alpha-chymotrypsin, alpha-lactalbumin, beta-lactoglobulin, papain, apotransferrin, trypsin, and trypsin inhibitor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The reactions of ozone with proteins and unsaturated fatty acids in reverse micelles. 815 24

Purified bovine milk proteins that were added to cultures of murine spleen cells significantly increased cell proliferation and production of immunoglobulin M. Casein and a whey mixture consisting of alpha-lactalbumin, bovine serum albumin, bovine gamma globulin, and beta-lactoglobulin (beta-LG) were stimulatory. Of the three beta-LG preparations that are commercially available (beta-LG containing variants A and B, purified variant A, and purified variant B), the unseparated mixture containing both the A and B variants showed the most immunomodulatory activity. Both alkaline treatment and trypsin digestion of the beta-LG preparation markedly reduced its effectiveness. Polymyxin B, while greatly diminishing the stimulatory effect of lipopolysaccharide, had no significant effect on either the enhancement of cell proliferation or the enhancement of immunoglobulin production by beta-LG. In the presence of S-(n-butyl)-homocysteine sulfoxamine, the stimulatory effect of beta-LG on cell proliferation and IgM production in vitro was markedly reduced.
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PMID:Immunostimulation of murine spleen cells by materials associated with bovine milk protein fractions. 971 Jul 50

Proteolytic digestion of alpha-lactalbumin by pepsin, trypsin and chymotrypsin yielded three polypeptide fragments with bactericidal properties. Two fragments were obtained from the tryptic digestion. One was a pentapeptide with the sequence EQLTK (residues 1-5) and the other, GYGGVSLPEWVCTTF ALCSEK (residues (17-31)S-S(109-114)), was composed of two polypeptide chains held together by a disulfide bridge. Fragmentation of alpha-lactalbumin by chymotrypsin yielded CKDDQNPH ISCDKF (residues (61-68)S-S(75-80)), also a polypeptide composed of two polypeptide chains held together by a disulfide bridge. The three polypeptides were synthesized and found to exert antimicrobial activities. The polypeptides were mostly active against Gram-positive bacteria. Gram-negative bacteria were only poorly susceptible to the bactericidal action of the polypeptides. GYGGVSLPEWVCTTF ALCSEK was most, EQLTK least bactericidal. Replacement of leucine (23) with isoleucine, having a similar chemical structure but higher hydrophobicity, in the sequence GYGGVSLPEWVCTTF ALCSEK significantly reduced the bactericidal capacity of the polypeptide. Digestion of alpha-lactalbumin by pepsin yielded several polypeptide fragments without antibacterial activity. alpha-Lactalbumin in contrast to its polypeptide fragments was not bactericidal against all the bacterial strains tested. Our results suggest a possible antimicrobial function of alpha-lactalbumin after its partial digestion by endopeptidases.
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PMID:Isolation and identification of three bactericidal domains in the bovine alpha-lactalbumin molecule. 1007 60

Bovine milk proteins alpha-lactalbumin (alpha-la) and beta-lactoglobulin (beta-lg) were hydrolysed with seven different proteolytic enzymes, and the effect of various hydrolysates on a genetically modified luminous Escherichia coli JM103 was tested in vitro with a bioluminescence assay for bacterial growth and metabolism. Undigested proteins did not inhibit the activity of tested E. coli JM103 at a concentration as high as 0.1 g ml-1. At the same concentrations, alpha-la hydrolysed with pepsin or trypsin and beta-lg hydrolysed with alcalase, pepsin or trypsin, showed a lower metabolic activity during the first 8 h of growth. The activity of E. coli JM103 in the presence of 25 mg ml-1 alpha-la or beta-lg hydrolysed with pepsin and trypsin was only 21% of the control after incubation for 6 h. The preliminary results indicated that ultrafiltration through 10 kDa and 1 kDa molecular mass cut-off membranes may be used to enrich bacteriostatic properties.
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PMID:The effect of alpha-lactalbumin and beta-lactoglobulin hydrolysates on the metabolic activity of Escherichia coli JM103. 1058 82

The aim of this study was to identify whey-derived peptides with angiotensin I-converting enzyme (ACE) inhibitory activity. The bovine whey proteins alpha-lactalbumin and beta-lactoglobulin were hydrolysed with pepsin, trypsin, chymotrypsin, pancreatin, elastase or carboxypeptidase alone and in combination. The total hydrolysates were fractionated in a two step ultrafiltration process, first with a 30 kDa membrane and then with a 1 kDa membrane. Inhibition of ACE was analysed spectrophotometrically. The peptides were isolated by chromatography and identified by mass and sequencing analysis. The most potent inhibitory peptides were synthesized by the 9-fluorenylmethoxycarbonyl solid phase method. Inhibition of ACE was observed after hydrolysis with trypsin alone, and with an enzyme combination containing pepsin, trypsin and chymotrypsin. Whey protein digests gave a 50% inhibition (IC50) of ACE activity at concentration ranges within 345-1733 micrograms/ml. The IC50 values for the 1-30 kDa fractions ranged from 485 to 1134 micrograms/ml and for the < 1 kDa fraction from 109 to 837 mg/ml. Several ACE-inhibitory peptides were isolated from the hydrolysates by reversed-phase chromatography, and the potencies of the purified peptide fractions had IC50 values of 77-1062 microM. The ACE-inhibitory peptides identified were alpha-lactalbumin fractions (50-52), (99-108) and (104-108) and beta-lactoglobulin fractions (22-25), (32-40), (81-83), (94-100), (106-111) and (142-146).
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PMID:Angiotensin I-converting enzyme inhibitory properties of whey protein digests: concentration and characterization of active peptides. 1071 43

Effects of Soybean Saponin on Protease Hydrolyses of beta-Lactoglobulin and alpha-Lactalbumin The effects of soybean saponin on tryptic and chymotryptic hydrolyses of whey proteins were evaluated. beta-lactoglobulin and alpha-lactalbumin became more sensitive to both trypsin and chymotrypsin by interacting with saponin in contrast to serum albumin. Soybean saponin was shown to have different effects on various proteins according to their nature.
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PMID:Effects of soybean saponin on protease hydrolyses of beta-lactoglobulin and alpha-lactalbumin. 1083 May 15

Methyl-, ethyl- and propyl-esters of beta-lactoglobulin, alpha-lactalbumin and beta-casein were prepared and then hydrolyzed with trypsin in various conditions. Resulting hydrolysates were analysed by SDS electrophoresis and RP-HPLC. The degree of hydrolysis of esterified samples was generally lower than those of the non-modified proteins. The highest degrees of hydrolysis were obtained at pH 7--8 with native and esterified protein samples. beta-Lactoglobulin propyl ester and beta-casein methyl ester yielded the lowest degrees of hydrolysis. Ethyl- and propyl-esters of beta-casein showed high resistance towards tryptic attack, even after 20 h of hydrolysis. SDS electrophoretic patterns of tryptic hydrolysates of native proteins showed bands corresponding to low molecular weights. Tryptic hydrolysates of esterified proteins showed bands with higher sizes. RP-HPLC profiles of tryptic hydrolysates of esterified samples showed peaks with longer elution times than those obtained with native proteins, indicating the presence of more hydrophobic peptide populations. A peptic pre-treatment improved tryptic action on esterified proteins. It resulted in a better resolution of RP-HPLC profiles and in a complete disappearance of the protein after 20 h tryptic hydrolysis.
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PMID:Susceptibility to trypsinolysis of esterified milk proteins. 1131 16

Whey proteins were modified by reaction with selected phenolic compounds (ferulic-, chlorogenic-, caffeic- and gallic acid) and related substances (quinic acid and p-quinone) as well as with extracts from coffee, tea, potato and pear at pH 9. The derivatives formed were characterized in terms of their physicochemical and digestion properties. The derivatization was accompanied by a reaction at the lysine and tryptophan side chains, whereby their content was decreased in comparison to that in the control whey proteins. Moreover, the solubility of the derivatives decreased over a broad pH range and the derivatization influenced the hydrophobe-hydrophile character of the whey proteins. The isoelectric points were shifted to lower pH values in the order of reactivity as follows: gallic acid > p-quinone > caffeic acid > chlorogenic acid. The other derivatives showed no or few changes compared to the control whey proteins. The formation of high molecular fractions was documented with SDS-PAGE. Especially the derivatives of chlorogenic-, caffeic-, gallic acid and p-quinone showed an increase in molecular weight of beta-lactoglobulin fraction from 18,300 to 20,000 Da. A dimer formation in molecular range 40,000 was also registered. MALDI-TOF-MS was applied to characterize the binding of the individual phenolic compounds or their oxidation products to the whey protein fractions, alpha-lactalbumin and beta-lactoglobulin. In vitro experiments showed that the digestion of the derivatized whey proteins with the enzymes of the gastrointestinal tract (trypsin, chymotrypsin, pepsin and pancreatin) was adversely effected. Similar results with regard to physicochemical characterization and digestion properties of the whey proteins treated with the applied extracts from plant beverages, fruit and vegetable were also documented. Coffee and tee were comparatively the most reactive extracts.
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PMID:Model studies on reactions of plant phenols with whey proteins. 1137 91

Characterization of the major human milk fat globular membrane proteins was carried out using proteomic techniques comprising two-dimensional polyacrylamide gel electrophoresis, followed by in situ PNGase F and trypsin digestion. Matrix-assisted laser desorption/ionization quadrupole time-of-flight and electrospray ionization mass spectrometry identified seven major protein components: alpha-lactalbumin, lysozyme precursor, beta-casein, clusterin, lactotransferrin, polymeric immunoglobulin receptor precursor, and human milk fat globule EGF-factor 8 protein. Sequence information on the protein-associated glycans was determined by matrix-assisted laser desorption-ionization quadrupole time-of-flight hybrid mass spectrometry. This glycan analysis revealed interesting fucosylation branching patterns which may be influential in maternal protection of the newborn against bacterial and viral pathogenic attack.
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PMID:Use of proteomic methodology for the characterization of human milk fat globular membrane proteins. 1181 2


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