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: UNIPROT:Q07644 (polypeptide)
72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A low molecular weight protein protease inhibitor was purified from Japanese horseshoe crab (Tachypleus tridentatus) hemocytes. It consisted of a single polypeptide with a total of 61 amino acid residues. This protease inhibitor inhibited stoichiometrically the amidase activity of trypsin (Ki = 4.60 X 10(-10) M), and also had inhibitory effects on alpha-chymotrypsin (Ki = 5.54 X 10(-9) M), elastase (Ki = 7.20 X 10(-8) M), plasmin, and plasma kallikrein. However, it had no effect on T. tridentatus clotting enzyme and factor C, mammalian blood coagulation factors (activated protein C, factor Xa and alpha-thrombin), papain, and thermolysin. The complete amino acid sequence of this inhibitor was determined and its sequence was compared with those of bovine pancreatic trypsin inhibitor (BPTI) and other Kunitz-type inhibitors. It was found that the amino acid sequence of this inhibitor has a high homology of 47 and 43% with those of sea anemone inhibitor 5-II and BPTI, respectively. Thus, this protease inhibitor appeared to be one of the typical Kunitz-type protease inhibitors.
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PMID:Purification and amino acid sequence of Kunitz-type protease inhibitor found in the hemocytes of horseshoe crab (Tachypleus tridentatus). 330 64

To investigate the molecular basis of the low-pH-mediated interaction of the bromelain-solubilized ectodomain of influenza virus hemagglutinin (BHA) with membranes, we have photolabeled BHA in the presence of liposomes with the two carbene-generating, membrane-directed reagents 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine ([125I]TID) and a new analogue of a phospholipid, 1-palmitoyl-2-[11-[4-[3-(trifluoromethyl)diazirinyl]phenyl][2-3H] undecanoyl]-sn-glycero-3-phosphocholine ([3H]-PTPC/11). With the latter reagent, BHA was labeled in a strictly pH-dependent manner, i.e., at pH 5 only, whereas with [125I]TID, labeling was seen also at pH 7. In all experiments, the label was selectively incorporated into the BHA2 polypeptide, demonstrating that the interaction of BHA with membranes is mediated through this subunit, possibly via its hydrophobic N-terminal segment. Similar experiments with a number of other water-soluble proteins (ovalbumin, carbonic anhydrase, alpha-lactalbumin, trypsin, and soybean trypsin inhibitor) indicate that the ability to interact with liposomes at low pH is not a property specific for BHA but is observed with other, perhaps most, proteins.
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PMID:Hydrophobic photolabeling identifies BHA2 as the subunit mediating the interaction of bromelain-solubilized influenza virus hemagglutinin with liposomes at low pH. 337 34

In addition to its ability to hydrolyze acetylcholine, purified eel acetylcholinesterase possesses a trypsin-like endopeptidase activity. The tryptic activity is associated with a serine residue at a site that is distinct from the esteratic site. To label both the esteratic and tryptic sites, the enzyme was incubated with the serine hydrolase inhibitor [3H]diisopropyl fluorophosphate. This compound labelled the protein in a biphasic manner, with both slow and rapid labelling kinetics. The time course of the rapid phase was similar to the time course of inactivation of the esteratic activity. The time course of the slow phase was similar to the time course of inactivation of the tryptic activity. Labelling of the nonesteratic site was inhibited by the trypsin inhibitor N alpha-p-tosyl-L-lysine chloromethyl ketone. The total number of sites labelled by [3H]diisopropyl fluorophosphate on eel acetylcholinesterase was 2.6 mol/280,000 g protein, whereas the number of tryptic sites was less (0.52 mol/280,000 g). The results suggest that a subpopulation of acetylcholinesterase molecules may possess tryptic activity. Extensive chromatography of the purified enzyme by ion-exchange and gel filtration failed to separate the labelled tryptic component from acetylcholinesterase. On sodium dodecyl sulfate-polyacrylamide gels, the labelled tryptic component comigrated with a polypeptide of 50,000 molecular weight, which is a major proteolytic digestion product derived from the intact acetylcholinesterase monomer. Because of its localization in many noncholinergic peptide-containing cells, acetylcholinesterase could act as a neuropeptide processing enzyme in these cells.
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PMID:Identification of a trypsin-like site associated with acetylcholinesterase by affinity labelling with [3H]diisopropyl fluorophosphate. 337 13

The fluorescence of lima bean trypsin inhibitor is due to a single tyrosine residue at position 69. The lifetime of this tyrosine fluorescence is 620 +/- 50 ps (mean +/- SD) and is little affected by addition of 0.88 M citrate, an efficient quencher of tyrosine fluorescence. The steady-state emission intensity is also only weakly reduced by the quencher. The tyrosine is thus not accessible to the citrate and is probably located in the interior of the protein. The high pK of the tyrosine supports this conclusion. The fluorescence anisotropy decay of the inhibitor's tyrosine can be fitted to a double exponential form, with time constants of about 40 ps and greater than or equal to 3 ns. The anisotropy at time zero is 0.19 +/- 0.015 (mean +/- SD), the same as for N-acetyl-L-tyrosinamide in viscous glycerol solution. The nanosecond component of the decay is consistent with rotation of the entire protein molecule. The 40-ps component demonstrates that the tyrosine has considerable freedom to move independently of the protein as a whole. This rotational correlation time is approximately what is observed for free tyrosine in aqueous solution. Since the polypeptide chain near tyrosine-69 is anchored by several disulfide bonds, the data argue that this interior portion of the protein consists of a rigid, immobile backbone embedded in fluid, mobile amino acid side chains.
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PMID:Fluorescence polarization decay of tyrosine in lima bean trypsin inhibitor. 346 71

The thiol protease was purified from adult Paragonimus ohirai by alpha 1-antitrypsin-Sepharose, Sephadex G-75 and CM-cellulose, measuring its activities to hydrolyze hemoglobin and tosyl-L-lysine alpha-naphthyl-ester. The purified protease showed a single band on polyacrylamide disc gel isoelectrophoresis as zymogram with Tos-Lys-NE and also by protein staining, and its pI was found to be 6.4. The molecular weight was calculated to be 29,000 by gel filtration and 27,000 by SDS-polyacrylamide gel electrophoresis as a single polypeptide. The protease hydrolyzed hemoglobin and Tos-Lys-NE optimally at pH 4.0 and 5.0, respectively. The both hydrolyzing activities were inhibited by alpha 1-AT and soybean trypsin inhibitor as well as thiol protease inhibitors such as antipain, E-64 and p-hydroxymercuriphenylsulfonate. These results indicate that this enzyme is a new type thiol protease.
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PMID:Purification and properties of a thiol protease from lung fluke adult Paragonimus ohirai. 351 8

A novel serine protease, which we have called IRCM-serine protease 1, was purified from both porcine neurointermediate and anterior pituitary lobes. The enzyme was inhibited by soybean trypsin inhibitor, pancreatic trypsin inhibitor, benzamidine, phenylmethyl-sulfonyl fluoride, and thiol reagents including HgCl2, p-chloromercuribenzoate, and 5,5'-dithiobis-(2-nitrobenzoic acid) and was resistant to lima bean trypsin inhibitor, alpha 2-macroglobulin, alpha 1-antitrypsin, and C1-esterase inhibitor. IRCM-serine protease 1 displayed "trypsin-like" specificity toward a number of tripeptide coumarin-containing substrates, with kcat/km values ranging from 10(4) to 10(6) M-1 S-1. The best substrate was benzyloxycarbonyl-L-Ala-L-Lys-L-Arg-4-methylcoumarin-7-amide with a kcat/Km value of 2.27 X 10(6) M-1 S-1. IRCM-serine protease 1, Mr = 169,000-190,000 determined by gradient gel electrophoresis and gel filtration, respectively, appears to be a homologous dimer. The monomeric subunits of the enzyme are composed of an Mr = 38,000 polypeptide chain which is modifiable by 125I-D-Tyr-Glu-Phe-Lys-Arg-CH2Cl, disulfide-linked to another polypeptide resulting in a subunit molecular weight of 88,000.
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PMID:A novel serine protease (IRCM-serine protease 1) from porcine neurointermediate and anterior pituitary lobes. Isolation, polypeptide chain structure, inhibitor sensitivity, and substrate specificity with fluorogenic peptide substrates. 352 55

Napin (1.7 S protein) is a basic, low molecular weight storage protein synthesized in rapeseed (Brassica napus) embryos during seed development. Napin is composed of two polypeptide chains with molecular weights of 9000 and 4000 that are held together by disulfide bonds. Comparison of the deduced amino acid sequence of a napin cDNA clone with that of napin peptide fragments established that napin is initially synthesized as a precursor of 178 residues. This polypeptide is subsequently processed through several proteolytic events, which ultimately generate the two mature napin chains, of 86 and 29 residues, respectively. Protein biosynthesis in vitro showed that the initial translation product (Mr 20,000) contains a signal sequence which is removed during transfer of the protein into the endoplasmic reticulum. Two additional peptides, of 22 and 19 residues, as well as the COOH-terminal residue, are also removed during maturation of napin, as deduced from the sequence comparison. Comparisons of the napin sequence with other known protein sequences established that there is a significant homology between napin and two other small seed proteins, the castor bean storage protein and a trypsin inhibitor from barley.
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PMID:Structure of the rapeseed 1.7 S storage protein, napin, and its precursor. 377 43

Cerebral neurons in monolayer cultures, subjected to 25 micrograms/ml trypsin, lose after 10 min about 43.5% and 40.5% of the ability to bind 125I-labeled tetanotoxin as measured at 0-4 degrees C and 37 degrees C respectively. These losses are maximal by 30 min and can be prevented by 1.5 mg/ml soybean trypsin inhibitor. Chymotrypsin but not collagenase or hyaluronidase is also effective in reducing binding of toxin to cells. The trypsin-insensitive toxin-binding activity can be further eliminated by treatment with sialidase or by cell extraction with methanol. Fixation of cells with 3.5% paraformaldehyde or 2% glutaraldehyde also results in a marked decrease of 52.4% and 25% respectively in the toxin-cell association. Methanol or sialidase but not trypsin removes the remaining binding activity. About one-third of the lipid-linked and protein-linked sialic acid is removed after sialidase treatment whereas 1% and 9.4% respectively are removed after trypsin treatment. The data are consistent with the possibility that, in addition to a sialic acid component, binding of tetanotoxin to nerve cells is facilitated by a trypsin-removable and formaldehyde-inactivated component. There was no evidence for a polypeptide to substitute gangliosides as receptors for tetanotoxin. On the contrary, solubility in organic solvents and interaction of the extracted products with labeled toxin remain the major proof that gangliosides are the putative receptors for tetanotoxin.
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PMID:Tetanus toxin receptors on nerve cells contain a trypsin-sensitive component. 394 36

Gap junctions (GJ) isolated from rat hearts in presence of the protease inhibitor phenylmethylsulfonylfluoride (PMSF) contain a Mr 44,000 to 47,000 major polypeptide and have a urea-resistant layer of fuzz on their cytoplasmic surfaces, whereas junctions isolated without PMSF are proteolyzed to a Mr 29,500 polypeptide by a serine protease and have smooth cytoplasmic surfaces (C.K. Manjunath, G.E. Goings & E. Page Am. J. Physiol. 246:H865-H875, 1984). Rat liver GJ isolated with or without PMSF contain a Mr 28,000 polypeptide and have smooth cytoplasmic surfaces. Here we examine the origin, type and inhibitor sensitivity of the heart protease; why similar proteolysis is absent during isolation of rat liver gap junctions; and whether the Mr 44,000 to 47,000 cardiac GJ polypeptide is the precursor of the Mr 29,500 subunit. We show that the Mr 44,000 to 47,000 polypeptide corresponds to the unproteolyzed connexon subunit; that proteolysis of this polypeptide occurs predominantly during exposure to high ionic strength solution (0.6 M KI) which releases serine protease from mast cell granules; that this protease is inhibitable with PMSF and (less completely) soybean trypsin inhibitor and chymostatin; and that in vivo degranulation of mast cells by injecting rats with compound 48/80 fails to prevent breakdown of cardiac GJ during isolation. The results support the concept that GJ from rat heart and liver differ in protein composition.
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PMID:Proteolysis of cardiac gap junctions during their isolation from rat hearts. 400 96

alpha 2-Macroglobulin (alpha 2M) is one of the major cadmium-binding proteins of human plasma. As determined with equilibrium dialysis, alpha 2M bound 4.6 (+/- 0.7) mol Cd2+ per mol protein with an apparent dissociation constant of (9.6 (+/- 5.0] X 10(-7) M. Methylamine-modified alpha 2M (alpha 2M-Me) had a similar affinity for Cd2+ (Kd,app = 5.3 X 10(-7) M), but fewer binding sites. Cadmium produced a small increase in the amidolytic activity of trypsin in the presence of alpha 2M and soybean trypsin inhibitor. Using the binding parameters determined from the equilibrium dialysis studies, the Cd2+ concentration which produced a half-maximal increase in amidolytic activity corresponded to saturation of all Cd2+-binding sites in one-half of the alpha 2M molecules. From these results, a model is proposed in which one Cd2+-binding site is present in each of the four polypeptide chains which compose alpha 2M.
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PMID:Cadmium binding to human alpha 2-macroglobulin. 608 4


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