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

---

Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Multiplication of influenza C virus in MDCK cell cultures increased with increasing concentrations of trypsin up to 160 micrograms/ml, whereas maximum growth of influenza A virus in the same culture was observed at a concentration of 10 micrograms/ml. In the presence of 160 micrograms of trypsin per ml MDCK cells showed the same or even higher susceptibility to various strains of influenza C virus compared with HMV-II cells, a human melanoma cell line that has been reported to have high susceptibility to the virus. Complete cleavage of the HE precursor protein of MDCK-grown influenza C virus into HE1 and HE2 subunits was achieved by trypsin at a concentration of 160 micrograms/ml, whereas only partial cleavage was observed at 10 micrograms/ml. The present results thus demonstrate that MDCK cell cultures supplemented with trypsin at a concentration of 160 micrograms/ml become highly susceptible to influenza C virus.
...
PMID:MDCK cell cultures supplemented with high concentrations of trypsin exhibit remarkable susceptibility to influenza C virus. 760 4

The sequences of two folliculostatic peptides of the fleshfly Neobellieria bullata have been determined recently. The first peptide (Neb-TMOF: H-NPTNLH-OH), originates from a 75 kDa precursor protein found in vitellogenic oocytes. The hexapeptide directly inhibits the synthesis of trypsin-like enzymes in the gut, and thus lowers the concentration of yolk polypeptides in the hemolymph. It also inhibits the biosynthesis of ecdysone in the larval ring gland. Therefore, it could also be named prothoracicostatic hormone (Neb-PTSH). The second peptide (Neb-colloostatin: H-SIV-PLGLPVPIGPIVVGPR-OH) acts on previtellogenic follicles and is a cleaved product of a collagen-like precursor molecule. Our results indicate that peptides that are cleaved from matrix proteins could act as growth-inhibiting factors. Gonadotropin releasing hormone (GnRH)-immunolike peptides were not identified, but progress is being made in the isolation and characterization of factors which stimulate cAMP production by the ovary. Using these results, a novel model of growth control in which matrix proteins play an important role as a potential source of growth regulators has been developed.
...
PMID:Folliculostatins, gonadotropins and a model for control of growth in the grey fleshfly, Neobellieria (sarcophaga) bullata. 762 97

Two distinct mechanisms have been previously identified for the transport of proteins across the chloroplast thylakoid membrane, one of which is unusual in that neither soluble factors nor ATP are required; the system requires only the transthylakoidal delta pH. We have examined this mechanism by studying the properties of one of its substrates: the extrinsic 23-kDa protein (23K) of photosystem II. Previous work has shown that this protein can be transported into isolated thylakoids as the full-length precursor protein; we show that the stromal import intermediate form of this protein is similarly translocation-competent. Gel filtration tests indicate that the stromal intermediate is probably monomeric. Protease sensitivity tests on both the initial in vitro translation product and the stromal import intermediate show that the presequence is highly susceptible to digestion whereas the mature protein is resistant to high concentrations of trypsin. The mature protein becomes very sensitive to digestion if unfolded in urea, or after heating, and we therefore propose that the natural substrate for this translocation system consists of a relatively unfolded presequence together with a tightly folded passenger protein. The ability of thylakoids to import pre-23K is destroyed by prior treatment of the thylakoids with low concentrations of trypsin, demonstrating the involvement of surface-exposed proteins in the import process. However, we can find no evidence for the binding of pre-23K or i23K to the thylakoid surface, and we therefore propose that the initial interaction of these substrates with the thylakoidal translocase is weak, reversible, and probably delta pH-independent. In the second phase of the translocation mechanism, the delta pH drives either the translocation and unfolding of proteins, or the translocation of a fully folded protein.
...
PMID:A monomeric, tightly folded stromal intermediate on the delta pH-dependent thylakoidal protein transport pathway. 782

Amyloid precursor protein forms that contain Kunitz protease inhibitor domains are released from activated platelets, T-lymphocytes, and leukocytes and inhibit trypsin, plasmin, and activated factor XI. We investigated the effects of amyloid precursor protein isoforms on activated Hageman factor (factor XII), activated factor X (Stuart factor), and thrombin. Recombinant amyloid precursor proteins with or without the Kunitz domain, 770 and 695 amino acids, respectively, were produced in insect cells by Baculovirus expression (BAC770 and BAC695). Neither BAC695 nor BAC770 inhibited human alpha-thrombin or activated factor X. The partial thromboplastin time was prolonged by both amyloid precursor proteins, only one of which, BAC770, contains the Kunitz protease inhibitor domain. Both forms of amyloid precursor proteins inhibited ellagic acid-induced activation of Hageman factor but did not inhibit activated Hageman factor. Bismuth subgallate, which is an insoluble analog of ellagic acid, lost its ability to activate Hageman factor on being exposed to BAC770. Inhibition of ellagic acid-induced activation of Hageman factor by both forms of amyloid precursor protein was enhanced by heparin. These findings suggested that the heparin-binding domain of amyloid precursor proteins is not in the Kunitz domain. This heparin-binding domain may block the activation of Hageman factor by negatively charged agents. Thus, amyloid precursor proteins may be involved in the control of hemostasis, properties not all dependent on the Kunitz domain.
...
PMID:Inhibitory action of amyloid precursor protein against human Hageman factor (factor XII). 784 73

The three-dimensional structure and disulfide connectivities of a 6-kDa protein isolated from the stigma of the ornamental tobacco Nicotiana alata has been determined by 1H NMR spectroscopy combined with simulated annealing calculations. The protein, termed C1, is a chymotrypsin inhibitor and is one of five homologous proteinase inhibitors that are proteolytically cleaved from a 40.3-kDa precursor protein. The other four proteinase inhibitors (T1 to T4) contain reactive sites for trypsin. The three-dimensional structure of C1 is generally well defined and contains a triple stranded beta-sheet as the dominant secondary structural feature. Several turns and a short region of 3(10) helix are also present. The putative chymotrypsin reactive site is present on an exposed loop which is less defined than the rest of the protein. The overall shape of C1 is disc-like and the N and C termini are exposed, supporting the proposal that this protein results from post-translational processing of the 40.3-kDa precursor protein.
...
PMID:The three-dimensional solution structure by 1H NMR of a 6-kDa proteinase inhibitor isolated from the stigma of Nicotiana alata. 808 44

A processing protease for the human immunodeficiency virus type I (HIV-I) envelope glycoprotein gp160 precursor has been purified to homogeneity from the post-nuclear membrane fraction of a human T4+ lymphocyte clone. Most of the processing activity was found to be present in the fractions of endoplasmic reticulum and Golgi apparatus of the cells. The purified enzyme has a monomeric structure with a molecular mass of 26 +/- 3 kDa, as judged by gel-permeation liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions. The purified enzyme converted gp160 to gp120 and gp41, showing a pH optimum of 6.5-7.0. Direct amino acid sequencing of the amino terminus of the product gp41 revealed that the cleavage site of gp160 was between Arg511 and Ala512. The enzyme activity was inhibited by trypsin-type protease inhibitors, but was not affected by CaCl2, MgCl2 or chelating agents. The properties of the purified enzyme are clearly distinct from those of processing proteases reported previously. Although the significance of the enzyme in vivo is not currently certain, judging from its cleavage specificity and subcellular localization, this endopeptidase appears to be a processing enzyme for the human immunodeficiency virus type I gp160 precursor protein in human T cells.
...
PMID:Processing protease for gp160 human immunodeficiency virus type I envelope glycoprotein precursor in human T4+ lymphocytes. Purification and characterization. 809 9

Picornavirus 3C proteinases (3Cpro) are cysteine proteinases but recent sequence analyses have shown that they are related to trypsin-like serine proteinases. Two models of 3Cpro structure have been presented. Both models indicate that residues His40 and Cys147 are members of the catalytic triad but the models differ in the designation of the third member of the catalytic triad, which is assigned as either Glu71 or Asp85. To test the importance of these four residues in the catalytic activity of 3Cpro of coxsackievirus B3, a member of the enterovirus subgroup of the picornavirus family, single amino acid substitutions were introduced at each of the four sites. All of these mutations resulted in the reduction or inactivation of autocatalytic cleavage of the 3C precursor protein expressed in Escherichia coli, suggesting that all of these residues are essential for the proteolytic reaction. The substitution of Cys147 with Ala abolished 3Cpro activity while the mutant in which Cys147 was replaced with Ser retained reduced proteolytic activity both in cis and in trans. Our results strongly support the proposal that Cys147 of 3Cpro functions as a nucleophile analogous to Ser195 of trypsin-like serine proteinases.
...
PMID:Site-directed mutagenesis of the putative active site residues of 3C proteinase of coxsackievirus B3: evidence of a functional relationship with trypsin-like serine proteinases. 838 63

Translocation and integration activities were assessed in Neurospora microsomes (nRM) after modification either by a sulfhydryl alkylating reagent or by a proteinase. A Neurospora in vitro system was programmed with RNA transcripts that encode the amino-terminal 194 amino-acid residues of the Neurospora plasma membrane H(+)-ATPase (pma194+) or the 262 amino-acid residues of the precursor of yeast invertase (preinv262). The processing of preinv262 was blocked in N-phenylmaleimide- and in trypsin-pretreated nRM. In contrast, the binding of preinv262 to microsomes was unaffected in the chemically alkylated nRM, but was affected in the trypsin-pretreated nRM. In the chemically alkylated vesicles, the integration of the pma194+ was not affected, but was partially blocked in the trypsin-pretreated vesicles. These data imply that trypsin-sensitive components are required for these activities in nRM, and that binding, translocation and integration can be differentiated by their sensitivity to chemical alkylation of sulfhydryl groups in nRM. Evaluated also were the effects of temperature on translocation and integration activities in the nRM. These were maximal at 20 degrees C, whereas the binding of preinv262 was maximal at 0 degree C. Taken together, these data demonstrate that the processing of preinv262 by nRM can be resolved into two steps: binding of the precursor protein to nRM and subsequent translocation into the lumen of the vesicles. Whereas, the integration of the pma194+ into nRM could not be resolved into separable steps. Taken together, these results are interpreted to imply that the initial association of truncated forms of the pma+ and the precursor of invertase to the surface of the nRM are distinct processes.
...
PMID:The initial association of a truncated form of the Neurospora plasma membrane H(+)-ATPase and of the precursor of yeast invertase with microsomes are distinct processes. 839 89

Streptomyces erythraeus produces an extracellular mammalian-type serine protease bearing trypsin-like substrate specificity. The gene encoding the protease was cloned and sequenced as an initial step for investigating its structure-function relationship by site-specific mutagenesis. The cloned gene is composed of an 816-bp open reading frame encoding 272 amino acid residues, suggesting that it is synthesized as a precursor protein containing a 42-residue prepropeptide. In the N-terminal prepropeptide portion, the tract of 30 residues from the initiator methionine has a typical signal sequence for Streptomyces and the remaining 12 residues are thought to comprise a propeptide. The cloned gene was replaced downstream of a strong promoter in a high expression plasmid, pSEV2, and expressed in Streptomyces lividans TK24. The gene product was secreted extracellularly and identified as an inactive precursor which consists of the mature enzyme and the 12-residue N-terminally extended peptide chain. The precursor protein was converted to a fully active mature form by limited proteolysis with alpha-chymotrypsin at the Phe-(-1)-Ile-1 bond. Protein sequence analysis revealed that, except for the C-terminal three residues, recombinant SET is identical with the native enzyme.
...
PMID:Molecular cloning, nucleotide sequence, and expression of the gene encoding a trypsin-like protease from Streptomyces erythraeus. 854 68

NA-proPI is a 40.3-kDa multidomain precursor protein found in the stigma of the ornamental tobacco Nicotiana alata. It is selectively targeted to the vacuole and, as the plant matures, is processed to produce a series of five 6-kDa proteinase inhibitors (one chymotrypsin and four trypsin reactive sites) which are thought to play a vital role in plant protection against insect pests. A putative sixth domain with a chymotrypsin reactive site is likely to be formed by three disulfide bridges linking the N- and C-terminal fragments of NA-proPI. This domain contains two distinct structural elements: a 54-residue sequence with high identity to each of the five repeated PI domains, and a nonrepeated 25-residue sequence at the C-terminus which is proposed to contain a vacuolar targeting peptide. The structure of the putative sixth domain was predicted using a combination of secondary structure prediction and homology modeling based on the known structure of one of the intact domains. A 26-residue peptide corresponding to the nonrepeated C-terminal sequence and encompassing the putative vacuolar targeting sequence was synthesized and its structure determined using 1H NMR spectroscopy and simulated annealing calculations. The peptide was found to adopt an amphipathic helical structure. The calculations based on NOE data suggested that the helix is curved, with a hydrophobic concave face and a hydrophilic convex face. This curvature is consistent with an observed periodicity in backbone NH chemical shifts. The structure of the entire sixth domain was modeled by combining the experimentally determined structure of the putative vacuolar targeting peptide with the homology model of the PI domain. In this model the alpha-helix of the putative targeting peptide protrudes from the otherwise compact PI domain. This observation is consistent with the requirement for targeting sequences to be relatively exposed for recognition by the sorting apparatus. As there is no consensus on the structure of vacuolar targeting sequences, this study provides a valuable insight into their potential mechanism of interaction with the cellular sorting apparatus.
...
PMID:Synthesis and structure determination by NMR of a putative vacuolar targeting peptide and model of a proteinase inhibitor from Nicotiana alata. 855 6


<< Previous 1 2 3 4 5 6 7 8 9 Next >>

---