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)

Trypsin digestion of HeLa nucleosomes produces the same series of discrete histone breakdown products observed previously by others during digestion of chromatin; thus, trypsin excises the NH2-terminal ends of the histones from the chromatin core particle. The resulting nucleoprotein complex sediments at 9 S, has an increased molecular ellipticity at 280 nm, and has DNase I-susceptible sites at 10 nucleotide intervals. Nucleosomes containing a 32P label at the 5'-DNA termini were digested sequentially with trypsin and DNase I. Following trypsin digestion, the segments of nucleosome DNA 20 to 35 and 60 to 80 nucleotides from the 5' end became more susceptible to DNase I, suggesting that these segments interact with the trypsin-sensitive regions of the histones.
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PMID:Localization of the sites along nucleosome DNA which interact with NH2-terminal histone regions. 89 23

Limited digestion with trypsin of both calf thymus H1 histone and the fragment 1--120 of the H1 molecule has resulted in the isolation of the fragment 35--120. This fragment assumes a globular structure under physiological conditions of pH and ionic strength. The variable N-terminal portion of the molecule, up to residue 34, is not required for the formation of the H1 globular structure. Proton nuclear magnetic resonance (NMR) and ultracentrifugation studies show that the H1 histone molecule consists of three distinct structural domains under structuring conditions: a random coil 'nose' consisting of 35 to 40 residues from the N-terminal end; a globular 'head' involving the next approximately 80 residues; and a random-coil 'tail' of the remainder of the molecule.
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PMID:Studies on the role and mode of operation of the very-lysine-rich histone H1 in eukaryote chromatin. The three structural regions of the histone H1 molecule. 90 38

Chromatin core particles, containing 140 base pairs (bp) of DNA plus the inner histones, can be nearly quantitatively formed either by reassociation from 2 M NaCl or by reconstitution from salt extracted histones and DNA. The reassociated or reconstituted particles appear to be identical with the native particles in all physical properties examined (sedimentation velocity, histone content, circular dichroism, and melting) as well as in their patterns of digestion by micrococcal nuclease, DNase I, and trypsin. In the presence of excess DNA, no "half-particles" are formed. In the presence of excess histone, aggregated structures are formed in addition to 11S core particles.
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PMID:Reconstitution of chromatin core particles. 92 32

Acid hydrolases from extracts of human blood leucocytes lyse Staph.aureus, Staph.albus and Strep.faecalis in vitro. The leucocyte enzymes can be substituted by a lytic mixture which contains crude trypsin, lysolecithin, phospholipase C and lysozyme, which lyse other bacterial species, e.g. E.coli and Listeria which are resistant to leucocyte enzymes. Bacteriolysis by the lytic agents is strongly inhibited by the anionic polyelectrolytes, heparin, chondroitin sulphate, DNA, dextran sulphate and other sulphated mucopolysaccharides, by the cationic materials, histone, protamine sulphate, leucocyte cationic proteins and polylysine. Other strong inhibitors are trypsan blue and congo red, the phospholipids phosphatidyl serine and ethanolamine, gold thiomalate, extracts of coffee and tea and the anti-inflammatory agents, ultracorten-H, and ultracortenol. Bacteriolysis is also strongly inhibited by normal human serum and by synovial fluids from patients with a variety of joint diseases. The inhibitors in these body fluids are associated with the globulin fractions. Since mixtures of anionic and cationic polyelectrolytes, at equimolar concentrations, failed to inhibit bacteriolysis by leucocyte enzymes, it is postulated that a delicate balance between positively and negatively charged inhibitors control the degradation of cell wall components of bacteria in inflamed areas. Such bacterial components, induce 'storage type' granulomas. The possible role played by polyelectrolytes in the control of the inflammatory process induced by leucocyte hydrolases will be discussed.
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PMID:The interaction of leukocytes and their hydrolases with bacteria in vitro and in vivo: the modification of the bactericidal and bacteriolytic reactions by cationic and anionic macromolecular substances and by anti-inflammatory agents. 94 4

We have examined the role by each histone in forming the structure of the nu-body. When DNAase I, DNAase II, trypsin and chymotrypsin attack chromatin, characteristic discrete DNA and protein digest fragments are produced. Using this restriction of accessibility as diagnostic for chromatin structure, we have examined complexes of DNA with virtually all possible combinations of histones. The results strongly support our previous conclusion (Camerini-Otero, Sollner-Webb, and Felsenfeld, 1976) that the arginine-rich histones are unique in their ability to create, with DNA a structure with many features of native chromatin. Acting together, slightly lysine-rich histones then modify this complex into one very similar to native chromatin. An analysis of the rate constants of staphylococcal nuclease digestion also confirms that the complex of H3, H4, and DNA is crucial to the structure of the nu-body.
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PMID:Chromatin structure as probed by nucleases and proteases: evidence for the central role of histones H3 and H4. 98 55

Psoriatic plaque scale was collected from untreated patients, homogenized, and subjected to chromatography on Sephadex and DEAE-cellulose to separate proteolytic enzymes. Five proteolytic enzymes were partially separated and characterized as to their substrate specificities, pH-optimum and inhibitor characteristics. A neutral trypsin-like protease, an alkaline histone hydrolyzing protease and a neutral chymotrypsin-like protease isolated were found to differ from those separated earlier from normal human skin using the same procedures for enzyme purification. The trypsin-like enzyme preparation was found to be an effective fibrinolytic activator and the histone hydrolyzing enzyme showed fibrinolytic activity. The possible roles of these proteases in the increased cell division rate of psoriatic plaque are discussed.
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PMID:Plasminogen activator and histone hydrolyzing proteases in psoriasis scales--possible role in increased cell division. 99 19

We had previously reported that the carcinogen, beta-propiolactone (BPL) reacted in vitro with histones in whole mouse skin chromatin and that among the histone classes BPL was preferentially bound to the lysine-rich histones H1 and H1 degrees. In order to determine if in vitro reaction of BPL with calf thymus histones resulted in binding of BPL to L-lysine, we synthesized the model compounds XI-N-(3-hydroxypropionyl)lysine (HPL) and xi-N-(I-carboxyethyl)lysine (CEL) from BPL and L-lysine. The alpha-amino group of L-lysine was protected from reaction with BPL by the formation of a copper chelate. Structures were assigned on the basis of infrared spectra, pKa values and chemical analyses. BPL was reacted in vitro with calf thymus histones and the BPL-reacted calf thymus histones and control calf thymus histones were digested with trypsin followed by pronase. The respective digests were each chromatograhed on a column of AA-15 cation-exchange resin. The elution profiles of the two digests were very similar except for the appearance of a new ninhydrin-positive peak (NNPP) in the eluate of the trypsin-pronase digest of BPL-reacted calf thymus histones. When compounds HPL and CEL were added to the trypsin-pronase digest of control calf thymus histones and the mixture chromatographed on AA-15, both compounds were resolved from the other peptide (or amino acid) peaks. HPL was eluted in the same fractions as NNPP, HPL and NNPP exhibited identical RF values on silica gel TLC with acidic, alkaline and neutral solvents. CEL was not identified as a product of the reaction between BPL and calf thymus histones.
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PMID:In vitro acylation of the xi-amino group of L-lysine in calf thymus histones by the carcinogen, beta-propiolactone. 100 30

One of the five main histone molecular species, H2A, of calf thymus was fractionated and purified on a large scale for chemical and physical studies. This was achieved by three methods, using different combinations of our CM-cellulose chromatographic technique with other chromatographic systems reported. Method I consists of chromatography first on CM-cellulose and then on Sephadex G-100, Method II first on Amberlite CG-50 and then on CM-cellulose and then on Bio-Gel P-10. Method I was successful when the starting material obtained by Johns' fractionation methods was contaminated by a small amount of H3 histone. Method II did not suffer from such a limitation but gave a low recovery of H2A on the first chromatography. Method III provided the purest preparations of H2A, together with highly purified H3, H4, and others, and is superior to methods previously reported for the large-scale preparation of H2A and other species from whole histone as regards the simplicity of the procedures and the purity and yield of the products. The preparation obtained by Method I was digested with trypsin [EC 3.4.21.4]. The resulting soluble and insoluble fractions of the digest were fractionated by column chromatography to give 20 small peptides and 2 large peptides, respectively, with high recoveries. The sequences of almost all the soluble peptides were determined; these, taking into account the recoveries of these peptides and the compositions of the insoluble peptides (19 and 29 residues), accounted for all the 129 amino acid residues of this histone.
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PMID:Calf thymus histone H2A. Purification and tryptic peptides. 101 Aug 39

Digestion of chromatin with DNase (nucleate 3'-oligonucleotidohydrolase, EC 3.1.4.7) releases 11-12S nucleoprotein particles. After extensive nuclease digestion, the DNA in these particles consists of a collection of eight discrete DNA fragments. When these nuclease-particles are treated with trypsin (EC 3.4.21.4), only 20 to 30 amino-acid residues are cleaved from histone N-terminals, the histone C-terminal segments being resistant. The resulting 5S nucleoprotein particles have now been shown on acrylamide gels to consist of a series of eight discrete DNA-containing bands. Four of these bands contain C-terminal cleavage fragments from four histones (III, IV, IIb2, and IIb1) tightly bound to them; a fifth contains fragments from only histones III and IV. The remaining three bands contain only DNA. Since these protein-free DNA bands were resistant to nuclease prior to trypsin treatment, they were presumably associated with histone N-terminal segments in the native structure. Trypsin, therefore, appears to split nuclease-particles, releasing two subfractions of DNA--one associated with protein, the other not. The data is compatible with a model in which the majority of DNA in the eukaryotic nucleus is folded into hairpin loops of double-stranded helix, each created by the concerted cross-linking action of 6 to 10 histones which interact to form a trypsin-resistant complex composed, for the most part, of all four major histones. These loops may further fold upon themselves to form the "nu" bodies that have been visualized by electron microscopy.
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PMID:Release of discrete subunits after nuclease and trypsin digestion of chromatin. 105 76

In 2 M NaCl, histones H2b, H2a, H3, and H4 form a heterotypic tetrameric complex made up of one chain of each histone. This complex has been analyzed by hydrodynamic techniques. It is indistinguishable from histones in chromatin by its resistance to trypsin, pattern of reactivity with 125I. and ability to form specific crosslinked products after treatment with formaldehyde. It is proposed that this complex is responsible for protecting the small DNA fragments produced by exhausting nuclease digestion of nuclei and that on the average two of these complexes protect the larger 180-200 base pair unit produced by partial treatment of nuclei with nuclease.
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PMID:Histones H2a, H2b, H3, and H4 form a tetrameric complex in solutions of high salt. 116 35


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