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 complete amino acid sequence of iron superoxide from Escherichia coli has been determined. The sequence was deduced from analysis of peptides obtained after cleavage of the carboxymethylated apoenzyme with trypsin. Stapholococcus aureus protease or CNBr. The polypeptide chain is made up of 192 residues and is easily aligned with the other known amino acid sequences of iron and manganese superoxide dismutases from various sources. The iron superoxide dismutase from E. coli shows a significantly higher homology with the iron enzyme from a different organism than with the manganese isoenzyme from E. coli.
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PMID:The primary structure of iron superoxide dismutase from Escherichia coli. 330 77

The ferredoxin was purified from the green alga, Chlamydomonas reinhardtii. The protein showed typical absorption and circular dichroism spectra of a [2Fe-2S] ferredoxin. When compared with spinach ferredoxin, the C. reinhardtii protein was less effective in the catalysis of NADP+ photoreduction, but its activity was higher in the light activation of C. reinhardtii malate dehydrogenase (NADP). The complete amino acid sequence was determined by automated Edman degradation of the whole protein and of peptides obtained by trypsin and chymotrypsin digestions and by CNBr cleavage. The protein consists of 94 residues, with Tyr at both NH2 and COOH termini. The positions of the four cysteines binding the two iron atoms are similar to those found in other [2Fe-2S] ferredoxins. The primary structure of C. reinhardtii ferredoxin showed a great homology (about 80%) with ferredoxins from two other green algae.
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PMID:Purification, properties and complete amino acid sequence of the ferredoxin from a green alga, Chlamydomonas reinhardtii. 335 5

Matrix-free cells from chick-embryo sterna were incubated with various concentrations of 2,2'-bipyridyl, an iron chelator that inhibits prolyl hydroxylase and lysyl hydroxylase. At concentrations in the region of 0.1 mM, significant effects on cartilage collagen hydroxylation and secretion were observed. When the underhydroxylated collagens were subsequently digested with chymotrypsin or chymotrypsin plus trypsin at 4 degrees C for 15 min, the minor cartilage collagen precursors (namely types IX and XI) were extensively degraded; type II procollagen was only partially susceptible and was converted into underhydroxylated collagen. The results demonstrate that there were significant differences in triple-helix stability among cartilage collagens such that the underhydroxylated minor collagen precursors were unable to attain a native structure under conditions where type II procollagen was successful.
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PMID:Underhydroxylated minor cartilage collagen precursors cannot form stable triple helices. 335 24

The uterus of the pig secretes large amounts of protein in response to progesterone. Estrogen alone has little effect but in combination with progesterone is synergistic at low doses and inhibitory at high doses. The responses of the uterus to progesterone require prolonged hormone treatment and are not immediate. The proteins secreted by the uterus of all species are believed to play some role in the nutritional and developmental support of the conceptuses, particularly during early pregnancy. Such a role is likely to be of greater importance in species such as the pig which possesses a noninvasive, diffuse-type of epitheliochorial placentation. A group of basic polypeptides dominates the uterine secretions of the pig. The best characterized is uteroferrin, a purple colored, iron-containing acid phosphatase which transports iron across the placenta. Three polypeptides which are found associated noncovalently with uteroferrin have been shown to be antigenically closely related to each other and to have arisen from a single precursor polypeptide. Their function is unknown. A family of plasmin/trypsin inhibitors which show sequence homology with bovine pancreatic trypsin inhibitor (aprotinin) has been well characterized and appears to control intrauterine proteolytic events initiated by the conceptuses. Several other proteins secreted in response to progesterone remain to be characterized and functionally defined.
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PMID:Hormonal control and function of secretory proteins. 345 17

Ribonucleotide reductase catalyzes the rate-limiting step in the formation of 2'-deoxyribonucleoside 5'-triphosphates. It consists of two nonidentical protein subunits, the nonheme iron subunit, and the effector-binding subunit. It has previously been shown that these two components making up the active enzyme species are not coordinately synthesized or degraded. It was found that the effector-binding subunit was more sensitive to proteolysis by chymotrypsin, to heating at 55 degrees C, and to the sulfhydryl reagents, pCMB and NEM. The nonheme iron subunit was more sensitive to trypsin treatment. ATP and dATP protected the effector-binding subunit from proteolytic inactivation. Neither ATP nor CDP protected the effector-binding subunit from inactivation by the sulfhydryl reagents. These data indicate that the protein properties of the two subunits of mammalian ribonucleotide reductase are significantly different.
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PMID:Differential sensitivities of the subunits of mammalian ribonucleotide reductase to proteases, sulfhydryl reagents, and heat. 351 48

The fhu operon of Escherichia coli K-12 comprises four genes, termed fhuA,C,D,B, which are involved in the uptake of iron-hydroxamate compounds. The fhuA gene encodes the outer membrane receptor protein. Cells that contained three copies of the fhuACD fragment on the thermoamplifiable plasmid pHK232 accumulated at 37 degrees C large amounts of the proFhuA protein. Most of the overproduced proFhuA protein was not translocated into the outer membrane but instead precipitated at the cytoplasmic side of the inner membrane, presumably at the sites of synthesis. Despite inhibition of export proFhuA synthesis continued. The precipitate formed was sedimented by centrifugation at 8,000 x g. The proFhuA protein could be solubilized in 1% sodium dodecyl sulfate. Replacement of sodium dodecyl sulfate by Triton X-100 resulted in a proFhuA protein which exhibited 10% of the phage T5 binding activity of renatured mature FhuA protein. Binding of the phage T5 was inhibited by the FhuA-specific ligands ferrichrome, albomycin and colicin M. Limited proteolysis of the isolated pro- and mature form of the FhuA protein with trypsin yielded similar oligopeptide patterns. Addition of ferrichrome affected trypsin cleavage of both proteins in the same way. The common proteolytic intermediates together with phage inactivation indicate a similar conformation of the pro- and mature form.
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PMID:Overproduction of the proFhuA outer membrane receptor protein of Escherichia coli K-12: isolation, properties, and immunocytochemical localization at the inner side of the cytoplasmic membrane. 353 58

Ribonucleotide reductase catalyzes the critical reaction in which the deoxyribonucleotides required for DNA replication are synthesized de novo. This enzyme consists of two non-identical protein subunits, both of which are required for enzymatic activity. These subunits consist of a non-heme iron and an effector-binding subunit. These subunits are not coordinately regulated as the cells pass from G1 to the S phase of the cell cycle. Studies carried out with the holoenzyme and the isolated subunits indicate that the effector-binding subunit is more susceptible to chymotrypsin and the sulfhydryl reagents, pCMB and NEM, than is the non-heme iron subunit. The non-heme iron subunit is more susceptible to trypsin than is the effector-binding subunit. The presence of ATP or dATP protects the effector-binding subunit from proteolysis by either trypsin or chymotrypsin. The loss of activity in the holoenzyme, as a result of proteolysis, parallels the loss of the particular subunit. These results demonstrate that the protein properties of the subunits are significantly different to account for the differential turnover. The binding of nucleotides to the effector-binding site(s), which in turn regulates ribonucleotide reductase activity, is very specific. Formycin 5'-triphosphate and etheno-ATP could not replace ATP in the CDP reductase reaction. 2',3'-DideoxyATP was 5-fold less active than dATP as a negative effector; etheno-dATP was not inhibitory. AraGTP and BuPdGTP could not replace dGTP as a positive effector of ADP reduction. BuPdGTP, but not araGTP, served as an inhibitor of CDP reduction. 2',3'-DideoxyTTP was much less active as either an activator of GDP reduction or an inhibitor of ADP reduction. These studies indicate that the binding to the allosteric sites is highly specific and suggest that the structural requirements for the binding of activators are different from the structural requirements for the binding of inhibitors.
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PMID:Protein properties of the subunits of ribonucleotide reductase and the specificity of the allosteric site(s). 354 6

The amino acid sequence of iron-superoxide dismutase from Pseudomonas ovalis was deduced by the analyses of peptides derived from limited hydrolysis of the aminoethylated or pyridylethylated apoprotein with trypsin, Staphylococcus aureus V8 protease, and dilute acid hydrolysis. The polypeptide chain contains 195 amino acid residues and has a calculated Mr of 21,421. The sequence is highly homologous (65% identity) to the recently published sequence of the iron-superoxide dismutase from Photobacterium leiognathi. It is also homologous to the known sequences of the manganese-superoxide dismutase by sharing 33-53% identical residues. Alignment of the superoxide dismutase sequences and the available structural information from X-ray crystallography suggest that the ligands to the iron in the P. ovalis superoxide dismutase are His-26, His-74, Asp-156 and His-160, which align with the ligands to the manganese in the Thermus thermophilus manganese-superoxide dismutase. The sequence information of the P. ovalis dismutase will facilitate refinement of the X-ray crystallographic data that are now available at 2.9 A resolution.
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PMID:Amino acid sequence of iron-superoxide dismutase from Pseudomonas ovalis. 366 46

The outer membrane proteins of Vibrio vulnificus including isolates from humans, seawater and an asari clam were examined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. A major outer membrane protein with an apparent molecular weight of 48,000 (48K protein) was common to all the strains grown in 3% NaCl-nutrient broth; however this 48K protein was not produced in any of the strains grown in chemically defined medium. Other major outer membrane proteins with molecular weights ranging from 33,000 to 40,000 varied in number, relative amount and molecular weight depending on the strain. One to three new outer membrane proteins with molecular weights ranging from 74,000 to 85,000 were produced in the cells grown in iron-deficient medium. The 48K protein and one or two major proteins with molecular weights ranging from 35,000 to 37,000 in the cells grown in 3% NaCl-nutrient broth were not solubilized by 2% SDS at 60 C for 30 min and were resistant to trypsin, indicating that they are porins. On the other hand, in cells grown in chemically defined medium, one or two major outer membrane proteins with molecular weights ranging from 33,000 to 40,000 might be porins.
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PMID:Composition of major outer membrane proteins of Vibrio vulnificus isolates: effect of different growth media and iron deficiency. 372 58

In this paper we describe the synthesis and characterization of magnetic microcapsules, intended for use in vivo, and which contain polyethyleneimine nucleophilic targets capable of trapping electrophilic carcinogens. The microcapsules, 15-50 microns in diameter, consist of a semipermeable cross-linked nylon membrane surrounding core polyethyleneimine and magnetite. These microcapsules can be readily manipulated and extracted from aqueous suspensions by magnetic fields. Core polyethyleneimine was released after membrane rupture by sonication. Magnetic hemoglobin microcapsules were also prepared but were unsuitable due to precipitation of hemoglobin within the core. Treatment by proteolytic enzymes that are present in the gastrointestinal tract caused microcapsule damage resulting in protein release, whereas polyethyleneimine microcapsules remained unaffected. After incubation with N-[methyl-14C]-N-nitrosourea, (1) the microcapsules retained covalently bound radiolabel, both in core polyethyleneimine and the microcapsule membrane. The efficiency of the binding of 1 was investigated by varying the polymer concentration during microcapsule manufacture. These type of microcapsules appear to have the desired properties for investigating carcinogen exposure in the mammalian gastrointestinal tract. They can be prepared easily and reproducibly, contain sufficient magnetite to allow their facile recovery from aqueous suspensions, are easily broken to release soluble core polyethyleneimine, and are stable to hydrolytic enzymes (trypsin) in vitro.
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PMID:Trapping of chemical carcinogens with magnetic polyethyleneimine microcapsules: I. Microcapsule preparation and in vitro reactivity of encapsulated nucleophiles. 378 50


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