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)

Two nuclease activities which were shown previously to copurify from extracts of log-phase Neurospora mycleia, a single-strand specific endonuclease activity (with DNA and RNA), and a strand nonspecific exonuclease activity (with DNA only) have been found to be associated with a single polypeptide. The enzyme has therefore been classified as an endoexonuclease. In logphase extracts, about 75% of this enzyme was found to exist in an inactive form which was activated in vitro either by endogenous phenylmethylsulfonyl fluoride sensitive proteinase(s) or by exogenous trypsin. The inactive form of endoexonuclease has been purified 45-fold in 15% yield free of the active enzyme. On electrophoresis in 6 M urea--polyacrylamide gels, it migrated at a much slower rate than the active enzyme, indicating that it is a less acidic and(or) larger protein than the active nuclease. The strong adsorption of this inactive enzyme on octyl-Sepharose suggests that the protein may have a relatively large hydrophobic domain. The protein may be a precursor of the active enzyme (a pronuclease) or a strong complex of enzyme with a proteinaceous inhibitor that is not dissociated in 6 M urea or during a variety of chromatographic procedures.
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PMID:Neurospora endoexonuclease and its inactive (precursor?) form. 14 85

Inter-alpha-trypsin inhibitor was isolated from human plasma and submitted to proteolytic degradation by plasmin. A split product of low molecular weight (18 000 daltons) is obtained by gel filtration or solubilisation in perchloric acid. This fragment reacts with an anti-inter-alpha-trypsin inhibitor immune serum and migrates as beta1 globulins. Its specific activity against trypsin (after absorption of residual plasmin on sepharose lysine) was estimated to be 900 mU1/mg. Thus one molecule of fragment can inhibit one molecule of trypsin. As well with native protein as with its fragment, complexes formed with trypsin can be dissociated by urea or sodium dodecyl sulfate. This fragment is similar to the small molecular weight inhibitors obtained directly by solubilisation in perchloric acid from serum, urine and bronchial secretions.
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PMID:[Proteolytic breakdown of human inter-alpha-trypsin inhibitor by plasmin (author's transl)]. 14 41

Protein kinase isolated from rabbit skeletal muscle can be reversibly converted from the cAMP dependent form to the indepent form by chaotropic salts and urea. A similar but irreversible conversion can also be induced by trypsin digestion of the holoenzyme. The dissociation of cAMP dependent protein kinase by low concentrations of thiocyanate raises the possibility of isolating both native regulatory and catalytic subunits. From various changes in enzymatic activity caused by urea and trypsin perturbation, it is proposed that the conversion of protein kinase from the cAMP dependent to the independent form is due primarily to preferential modification of the regulatory subunit of the holoenzyme.
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PMID:Rabbit skeletal muscle protein kinase. Conversion from cAMP dependent to independent form by chemical perturbations. 16 29

Previous studies have shown that urea and acetamide traverse the erythrocyte membrane by way of facilitated diffusion. The nature of this selective pathway is unknown. The present studies investigate the effects of proteolytic enzymes and crosslinking agents on amide transport. Cleavage of the erythrocyte membrane surface by pronase or trypsin had no effect on urea and acetamide permeability or inhibition by phloretin. These findings suggest that the sialoglycopeptide segment of the sialoglycoproteins is not critical to urea and acetamide transport. In addition, extensive crosslinking of membrane proteins with glutaraldehyde had no effect on amide transport in the absence or presence of phloretin.
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PMID:Membrane proteins and urea and acetamide transport in the human erythrocyte. 16 54

Flounder muscle (Pseudopleuronectes americanus) glyceraldehyde-3-phosphate dehydrogenase was characterized as to its stability towards various inactivating treatments in the presence and absence of the enzyme cofactor, NAD. Incubation of a partially purified enzyme preparation at urea concentrations greater than 2 M produced a very rapid inactivation. NAD greatly reduced the rate of inactivation at all the urea concentrations tested. Incubation of each of the three major muscle enzyme forms in 0.1 percent trypsin or chymotrypsin for forty-five minutes decreased the activity of each form by 65 percent and 55 percent, respectively. NAD (5mM) afforded complete protection to each enzyme form from proteolytic digestion by these two enzymes. Exposure of each form to 50 degrees or 20 mM ATP also led to gross inactivation which could be greatly reduced if the respective incubations were performed in the presence of 5mM NAD. NAD was also found to be required for the renaturation of the unfolded urea-denatured subunits to form the active tetramer.
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PMID:Effect of NAD on flounder muscle glyceraldehyde 3-phosphate dehydrogenase. 17 55

Limited tryptic digestion of human serum low-density (LD) lipoprotein (rho 1.024-1.045 g/ml) under defined conditions permitted isolation by gel filtration chromatography of a stable, protein-deficient lipoprotein; the liberated protein was separated as a mixture of peptides of low molecular weight (less than 5000). Comparison of the chemical, physical and immunological characteristics of the trypsin-treated LD-lipoprotein with those of the native preparation revealed several differences, including (a) a diminished protein content (loss of some 20-25% of the total protein of LD-lipoprotein) and increased proportions of the various lipid components, except for triglyceride (probably resulting from a loss of bound free fatty acids with the liberated peptides); (b) a greater heterogeneity in particle size and slightly larger mean diameter; (c) a lower hydrated density and greater peak sf rate than the native LD-lipoprotein (d) an increased net negative charge; and (e) a partial immunological identity between LD-lipoprotein and the corresponding trypsin-treated fraction. While the amino acid compositions of the protein moieties of LD-lipoprotein and of trypsin-treated LD-lipoprotein were essentially identical, trypsin-treated apo-LD-lipoprotein was distinct in its complete solubility in urea-containing buffers at high concentrations, and also in its partial solubility in buffers lacking denaturing agents. Comparison of the apoproteins of the native and trypsin-treated LD-lipoproteins by electrophoretic techniques based on molecular weight revealed a transformation of the high-molecular weight material (greater than 250 000) characteristic of apo-LD lipoprotein into several polypeptide species (10 major forms) ranging in size from 161 500 to about 10 000. The largest of these (band b1: 161 500) could be completely dissociated into smaller components (b2: 93 500 and b3: 77 000) upon extensive heat treatment at 90 degrees C. Electrophoresis of the soluble fraction of apo-LD-lipoprotein and of that from its trypsin-treated counterpart in polyacrylamide gels containing urea at basic pH showed the disappearance of the small amounts (less than 5%) of C apoproteins of apo-LD-lipoprotein upon tryptic treatment. These results, which were highly reproducible in LD-lipoprotein preparations from different individuals, suggest that trypsin-treated LD-lipoprotein may provide a model for investigation of the organisation and structural role of the prinicipal apoprotein (apolipoprotein-B) in the LD-lipoprotein molecule.
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PMID:Limited tryptic digestion of human serum low-density lipoprotein: isolation and characterisation of the protein-deficient particle and of its apoprotein. 21 15

A protein, present in bovine seminal plasma, initiates forward motility in immature, immotile caput spermatozoa that have been incubated with a cyclic AMP phosphodiesterase inhibitor. An improved motility assay was developed to study this process and the protein involved. This forward motility protein exhibits multiple forms when fractionated on the basis of charge or molecular weight. Molecular sieving in urea or sodium dodecyl sulfate and dithiothreitol results in a single peak of activity which will re-form the larger aggregates in the absence of these agents. The molecular weight of this monomeric motility protein, as estimated from molecular sieving under these dissociating conditions, is 37,500. The forward motility protein can be partially purified by heat treatment, gell chromatography in urea, and affinity chromatography on concanavalin A/agarose. Enzymatic treatments further suggest a glycoprotein nature, i.e. treatment with beta-galactosidase, neuraminidase, alpha-mannosidase, or galactose oxidase reduces its activity by 50%; treatment with trypsin completely abolishes forward motility protein activity. On the basis of concurrent studies on the activity, properties, and distribution of forward motility protein in bovine body fluids, it is suggested that this protein is involved in the development of the capacity for motility as sperm traverse the epididymis.
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PMID:Bovine sperm forward motility protein. Partial purification and characterization. 21 Nov 30

The serological characterization of virus isolates from verrucae vulgares and plantar warts revealed that HPV 1 and HPV 4 are present in about 50% of these warts with HPV 1 being more prevalent, especially in plantar warts. Parallel to the high incidence of HPV 1 infections, about 50% of non-selected young adults contained antibodies against HPV 1. Only HPV 4 particles, however, reacted with serum from a patient with epidermodysplasia verruciformis when tested by immuno-electron microscopy. An examination of HPV 1 proteins indicated that the major structural proteins VP2 and VP3 are trypsin sensitive. Tryptic degradation leads to distinct polypeptides with molecular weights between 37,000 and 23,000 which may be correlated to minor protein components of HPV 1 preparations. HPV 1 histone-like proteins, which co-migrate with purified cellular histones in SDS gel electrophoresis were analyzed in an acetic acid urea system. It was shown that H3- and H4-like proteins differ from cellular histones. The reason for this difference and its meaning are discussed.
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PMID:Characterization of proteins of human papilloma viruses (HPV) and antibody response to HPV 1. 21 77

When nucleosomal core histones were isolated from rat liver nuclei incubated with [14C]NAD+ and fractionated into the individual components (H2A, H2B, H3, and H4), [14C]adenosine diphosphate ribose (ADP-Rib) was found to be associated with all of them. However, while about 15% of the H2B molecules were modified, less than 2% of the other fractions contained radioactive ADP-Rib. The nucleotide attached to H2B was identified as a single monomer of ADP-Rib. On subjectint H2B to electrophoresis in polyacrylamide gels containing 2.5 M urea and 0.9 N acetic acid, one single band of H2B with 5% less mobility than the unomdified control was obtained. The linkage between H2B and ADP-Rib was rapidly hydrolyzed with 0.1 N NaOH or with 1 M neutral hydroxylamine. Hydrolysis of ADP-ribosylated H2B with trypsin generated a single peptide linked to ADP-Rib, which corresponded to the sequence Pro-Glu-Pro-Ala-Lys. We were able to dansylate the NH2-terminal proline, which proved that the imino group of this amino acid was not substituted. These findings, together with the chemical properties of the linkage, which were typical of those of an ester-like bond, strongly suggest that the ADP-Rib residue was linked to the gamma-COOH group of the glutamic acid in position 2 of H2B.
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PMID:ADP ribosylation of rat liver nucleosomal core histones. 21 26

Properties of photoexcitable luciferase are compared with those of luciferase, both isolated from the bacterium Beneckea harveyi. The proteins have the same molecular weight, are similarly charged at pH 8, and can be inactivated, with comparable efficiencies, by antibodies against either pure luciferase (a heterodimeric protein) or individual subunits thereof. Compared with luciferase, photoexcitable luciferase has a broader pH range for optimal activity, is more stable under acidic conditions, is less stable under alkaline conditions, and is more resistant at neutral pH to inactivation by heat, urea, and trypsin; A flavine-like chromophore, designated B, can be isolated from photoexcitable luciferase. The binding of B to luciferase restores all the properties characteristic of photoexcitable luciferase. Moreover, photoexcitable luciferases from mutants selected to have heat labile luciferases are also thermally unstable. It is concluded that photoexcitable luciferase actually consists of a luciferase-B complex which is conformationally distinct from luciferase under certain conditions.
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PMID:Photoexcited bacterial bioluminescence. Identity and properties of the photoexcitable luciferase. 23 73


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