Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.64 (proteinase K)
 4,071 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A protease delivery system was developed for the exclusive and controlled digestion of proteins exposed at the morphological inside (periplasmic surface) of Rhodobacter sphaeroides chromatophores. In this procedure, proteinase K is encapsulated within large unilamellar liposomes which are fused to the chromatophores in the presence of Ca2+ ions. The liposomes were prepared by a detergent dialysis procedure from native phosphatidylglycerol and found to undergo rapid bilayer fusion with purified chromatophore preparations above a threshold concentration of 12.5 mM CaCl2. The fusion process was complete within 10 min at 35 mM Ca2+ with about 80% of the pigment located in the fusion products. Electron micrographs of freeze-fracture replicas confirmed the intermixing of the lipid bilayers and the unilamellar structure of the fused membrane vesicles. The procedure did not affect the labile B800 chromophore of the B800-850 antenna complex, but reduced slightly the absorption due to the B875 core antenna. Emission from both light-harvesting complexes was increased in the fused membranes, suggesting a partial dissociation of photosynthetic units in the expanded bilayer. The results, together with those presented in the following paper (Theiler, R., and Niederman, R. A. (1991) J. Biol. Chem. 266, 23163-23168), demonstrate that this new method fulfills the stringent requirements for a successful delivery of macromolecules to the chromatophore interior.
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PMID:Localization of chromatophore proteins of Rhodobacter sphaeroides. I. Rapid Ca(2+)-induced fusion of chromatophores with phosphatidylglycerol liposomes for proteinase delivery to the luminal membrane surface. 174 15

The three-dimensional crystal structure of thermitase complexed with eglin-c in the presence of 100 mM calcium has been determined and refined at 2.0-A resolution to a R-factor of 16.8%. This crystal structure is compared with previously determined structures of thermitase at 0 and 5 mM calcium concentration. In the presence of 100 mM calcium all three calcium binding sites in thermitase are fully occupied. At 100 mM CaCl2 the "weak" calcium binding is occupied by a calcium ion, which is chelated by three protein ligands and four water molecules in a pentagonal bipyramid geometry. Thermitase has, apparently, a monovalent and divalent cation binding position at 2.5-A distance from each other at this site. At low calcium concentrations the monovalent-ion position is occupied by a sodium or potassium ion. The "medium strength" binding site shows in the presence of 100 mM CaCl2 a square antiprism arrangement with eight ligands, of which seven are donated by the protein. At low calcium concentrations we observe a distorted pentagonal bipyramid coordination at this site. The largest difference between these two conformations is observed for ligand Asp-60, which has two conformations with 0.8-A difference in C alpha positions. The "strong" calcium binding site has a pentagonal bipyramid coordination and is fully occupied in all three structures. Structural changes on binding calcium to the weak and "medium strength" calcium binding sites of thermitase are limited to the direct surroundings of these sites. Thermitase resembles in this respect subtilisin BPN' and does not exhibit long-range shifts as have been reported for proteinase K.
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PMID:Calcium binding to thermitase. Crystallographic studies of thermitase at 0, 5, and 100 mM calcium. 199 69

The cryptomonad cell has presumably arisen by a secondary symbiotic event involving two eukaryotes, and thus is composed of four different DNA-containing compartments (nucleus, nucleomorph, plastid, and mitochondrion). In the present paper, the isolation and quantitative DNA estimation of the host cell nucleus and the nucleomorph, a vestigial eukaryotic nucleus, is presented. In the presence of CaCl2, the host nucleus could be isolated from cells lysed by Triton X-100. For isolation of the nucleomorph, cells were slightly fixed with glutardialdehyde and thereafter, lysed by treatment with proteinase K and Triton X-100, leaving an intact nucleomorph-pyrenoid complex. Nuclei were further purified by isopycnic Percoll density gradient centrifugation. Purity and quality of the two nuclear fractions were checked by means of DAPI-epifluorescence microscopy and electron microscopy. The DNA content of the host nucleus and nucleomorph, determined by the diphenylamine method and by means of quantitative microspectrofluorometry, respectively, was found to be more than 700 times higher in the host nucleus than in the nucleomorph.
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PMID:Isolation and preliminary characterization of the nucleus and the nucleomorph of a cryptomonad, Pyrenomonas salina. 208 36

Thirty-four strains of enteroinvasive Escherichia coli (EIEC) were examined for their ability to agglutinate erythrocytes from different animal species. All strains cultured in Casamino acid-yeast extract medium in the presence of 1 mM CaCl2 at 37 C for 16-22 hr induced maximal expression of hemagglutination (HA) of broad spectrum erythrocytes. The strongest HA was observed with guinea-pig erythrocytes followed by human (O type), rat, mouse, rabbit and sheep erythrocytes. All the strains failed to agglutinate chicken erythrocytes. HA was resistant to D-mannose, D-glucose, D-galactose, L-fucose, and D-fructose. Also HA was resistant to ethylene diamine tetraacetic acid (EDTA) and Na metaperiodic acid, an oxidizing agent. However, it was heat labile and completely inhibited by proteolytic enzymes such as proteinase K and trypsin, suggesting that the possible hemagglutinin of EIEC associated with the cell surface is a proteinaceous substance.
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PMID:Study of hemagglutinating property of enteroinvasive Escherichia coli from various geographical locations. 856 44