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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

(1) The characteristics of protein synthesis in microsomal and synaptosomal fractions from rat brain were examined. A high sensitivity to ribonuclease and to cycloheximide, and the need for the presence of pH5 enzymes distinguished protein synthesis in microsomal fractions from protein synthesis in synaptosomes. (2) Under various conditions of incubation synaptosomal fractions prepared in sucrose showed limited protein synthesis compared with synaptosomal fractions prepared by using Ficoll. Such discrepancies could not be attributed to: (i) animal age, (ii) the metabolic state of the synaptosomal fraction, (iii) the absence of bivalent cations in the incubation medium or (iv) the temperature. (3) Protein synthesis in synaptosomal fractions was inhibited 50-65% by cycloheximide, 38-50% by chloramphenicol, 95% by puromycin, 70% by azide and 40% by deoxyglucose; ribonuclease had only a negligible inhibitory effect. (4) As a first approximation to the localization of the protein-synthetic machinery present in the synaptosomal fraction, the distribution of enzymes and radioactivity in subfractions of prelabelled synaptosomes was determined after osmotic shock with water. Approximately 60% of the total protein synthesis in the synaptosomal fraction occurred in the intraterminal mitochondria. (5) Protein synthesis in the intraterminal mitochondria did not show any fundamental difference from synthesis in somatic mitochondria, with respect to inhibition by cycloheximide and chloramphenicol. (6) It was concluded that if extramitochondrial protein synthesis occurs in synaptosomes, it must be very low.
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PMID:Protein synthesis by synaptosomes from rat brain. Contribution by the intraterminal mitochondria. 444 74

Franklin, Richard M. (Institut de Recherches sur le Cancer, Villejuif, Seine, France), and Nicole Granboulan. Ultrastructure of Escherichia coli cells infected with bacteriophage R17. J. Bacteriol. 91:834-848. 1966-Ultrastructural changes in Escherichia coli cells infected with ribonucleic acid (RNA) bacteriophage R17 were studied under conditions of one-step growth. No morphological alterations were seen during the latent period. During the period of rapid viral synthesis, a fibrillar lesion surrounded by ribonucleoprotein particles was observed in a polar region. Late in infection, paracrystalline arrays of virions were found in over 90% of the cells. When protein synthesis was blocked by in over 90% of the cells. When protein synthesis was blocked by chloramphenicol at 20 min postinfection, allowing continued viral RNA synthesis without production of coat protein, a dense fibrillar area appeared in a paranuclear region. Cytochemical studies were done on cells embedded in hydroxypropyl methacrylate, a water-miscible embedding agent. The paracrystalline arrays of virions were digested after extensive treatment with either pepsin or ribonuclease. Shorter digestion with the pepsin resulted in better definition of the crystal regions. The fibrillar area found in chloramphenicol-treated cells was digested by ribonuclease but not by pepsin, and was also resistant to lead extraction. This region probably represents a pool of virus-specific RNA.
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PMID:Ultrastructure of Escherichia coli cells infected with bacteriophage R17. 532 73

Epithelial cells and the outer cortex from lenses of 1-day-old calves contain polyribosomes occurring in clusters of five to ten monomers. The structure of these clusters is not affected by trypsin treatment up to 10mug./ml. of ribosomal suspension. When the whole lens is used as starting material the polyribosomal preparations are strongly contaminated with non-ribosomal material, which gives rise to ribosomal aggregates having the appearance of giant polyribosomes. These structures are sensitive to trypsin treatment but resist ribonuclease treatment. The electrophoretic pattern of the contaminating material resembles that of water-soluble lens protein.
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PMID:Structural aspects of eye lens polyribosomes. 567 26

Aldehyde-fixed rat tissues were variously dehydrated and impregnated in water-miscible 2-hydroxypropyl methacrylate (HPMA) containing 3 to 20 per cent water and 0.1 per cent alpha,alpha-azobisisobutyronitrile as catalyst for subsequent polymerization with ultraviolet light. Heat polymerization was also effective. Blocks of embedded tissue readily gave ultrathin sections, which required staining by uranyl acetate and/or lead stains to give adequate contrast for electron microscopy. The ultrastructure of pancreas, kidney, muscle, and intestine was well preserved by aldehyde fixation alone. Use of postfixation in osmium tetroxide or direct osmium tetroxide fixation was unsatisfactory. The fine structure of aldehyde-fixed liver from fasted rats was well preserved, whereas that from normal rats showed considerable disorganization and collapse, apparently because of extraction of glycogen during the embedding procedure. Enzymatic extraction of proteins by pepsin and of ribonucleic acid by ribonuclease after either formaldehyde or glutaraldehyde fixation was rapidly effected by direct treatment of ultrathin sections with solutions of the enzymes. In contrast, no digestion of chromatin by deoxyribonuclease could be detected. In spite of this present limitation, HPMA appears to have several advantages over earlier water-miscible embedding media for electron microscopy and to be particularly suitable for ultrastructural cytochemistry.
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PMID:Hydroxypropyl methacrylate, a new water-miscible embedding medium for electron microscopy. 585 16

Spectrin in isolated erythrocyte membranes is known to undergo tetramer to dimer transformation upon hypotonic incubation at 37 degrees C. In the present study, we detect no such transformation in intact erythrocytes in which hypotonicity is achieved by valinomycin treatment followed by hypotonic swelling. The inhibition of spectrin tetramer to dimer transformation is attributable to intracellular hemoglobin, since the addition of hemoglobin to isolated membranes or spectrin extracts blocks a similar spectrin transformation. However, the inhibitory effect is not limited to hemoglobin; other proteins including heme-containing proteins and basic proteins such as cytochrome c, ribonuclease, and albumin are also effective. The magnitude of their effect is proportional to the increased pI value of these proteins. We conclude that the stabilizing effect of these proteins on spectrin tetramers under hypotonic conditions is partly due to their non-ideality, which excludes water from spectrin and thus increases the effective concentration of spectrin, and to their electrostatic interactions with spectrin. In addition, promotion of spectrin self-association by hemoglobin under hypotonic conditions increases the stability of membrane skeletons against mechanical shearing. More importantly, the hemoglobin effect on spectrin self-association is demonstrable at physiological hemoglobin concentration, pH, and osmolarity, suggesting that in intact red cells the spectrin dimer-dimer association, as well as the membrane skeletal structure, is strengthened by intracellular hemoglobin.
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PMID:Hemoglobin enhances the self-association of spectrin heterodimers in human erythrocytes. 608 50

We make use of the known exchange rates of individual amide proton in the S-peptide moiety of ribonuclease S (RNAase S) to determine when during folding the alpha-helix formed by residues 3 to 13 becomes stable. The method is based on pulse-labeling with [3H]H2O during the folding followed by an exchange-out step after folding that removes 3H from all amide protons of the S-peptide except from residues 7 to 14, after which S-peptide is separated rapidly from S-protein by high performance liquid chromatography. The slow-folding species of unfolded RNAase S are studied. Folding takes place in strongly native conditions (pH 6.0, 10 degrees C). The seven H-bonded amide protons of the 3-13 helix become stable to exchange at a late stage in folding at the same time as the tertiary structure of RNAase S is formed, as monitored by tyrosine absorbance. At this stage in folding, the isomerization reaction that creates the major slow-folding species has not yet been reversed. Our result for the 3-13 helix is consistent with the finding of Labhardt (1984), who has studied the kinetics of folding of RNAase S at 32 degrees C by fast circular dichroism. He finds the dichroic change expected for formation of the 3-13 helix occurring when the tertiary structure is formed. Protected amide protons are found in the S-protein moiety earlier in folding. Formation or stabilization of this folding intermediate depends upon S-peptide: the intermediate is not observed when S-protein folds alone, and folding of S-protein is twice as slow in the absence of S-peptide. Although S-peptide combines with S-protein early in folding and is needed to stabilize an S-protein folding intermediate, the S-peptide helix does not itself become stable until the tertiary structure of RNAase S is formed.
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PMID:Amide proton exchange used to monitor the formation of a stable alpha-helix by residues 3 to 13 during folding of ribonuclease S. 609 89

A cell suspension derived from a single murine spontaneous mammary adenocarcinoma was resolved on a linear gradient of Ficoll, into twelve distinct neoplastic cell subpopulation. A second cell suspension, also derived from a single murine mammary adenocarcinoma was first treated with vibrio cholera neuraminidase (VCN) then was resolved on an identical gradient of Ficoll into twelve distinct subpopulation. Each cell population was seeded and allowed to proliferate. The cell subpopulations differed in their doubling time, cloning efficiency, tumorigenicity and metastatic capacity. Although in vivo the murine spontaneous mammary adenocarcinoma (SMMAdCa) never metastasized, SMMAdCa-10 subpopulation metastasized into lymph nodes and lungs. All VCN-modified subpopulations were non-oncogenic. Cells from each population were used to immunize groups of syngeneic mice. The spleens of each group were pooled and Immune-RNA's were extracted with the phenol-water standard technique. The IRNA's preparations stimulated DNA synthesis in normal murine spleenocytes. The various I-RNA's differed in their biological activities, base composition and their sensitivity to ribonuclease.
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PMID:Enzymically-mediated changes in murine mammary adenocarcinoma cell membrane induces changes in lymphoid tissue immune ribonucleic acids. 616 33

Ribonuclease hydration in wide concentration and temperature range using differential scanning microcalorimetry and NMR technique was studied. The temperature- concentration equilibrium diagram for H2O--ribonuclease system was suggested. Protein hydration in D2O was shown to be higher than in ordinary water. NMR measurements in dilute protein solutions showed that cooperative temperature denaturation was followed by solvation changes. Models of globular protein hydration are discussed.
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PMID:[Ribonuclease hydration and its heat stability in solutions of H2O and D2O]. 624 23

Heat denaturation of ribonuclease in diluted water solutions was studied by means of proton magnetic relaxation, microcalorimetry and viscosity. It has been shown that heat denaturation of ribonuclease is a one stage process; it involves the whole globule and is accompanied by changes in the state of salvated (water) molecules. A redistribution of water molecules in the hydrate "envelope" of protein changes the character of proton magnetic relaxation of the whole solvent.
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PMID:[Proton magnetic relaxation and thermodynamic parameters of ribonuclease solutions during thermal denaturation]. 624 33

We have designed and synthesized a model pentadecapeptide predicted to have the essential sequence information needed to form a stable and enzymatically active noncovalent complex with bovine pancreatic ribonuclease S-protein. The model peptide sequence, based on the conformational approach of simplifying the native sequence in a manner consistent with retention of essential noncovalent contacts and of secondary structure features, contained alanine at all positions except for Glu 2, Lys 7, Phe 8, Arg 10, His 12, and Met 13. The peptide was synthesized by the Merrifield solid phase method. The circular dichroism spectra of the purified model peptide in water and trifluoroethanol indicated a tendency to form an alpha-helical structure similar to that found for native S-peptide. The model peptide formed a stable complex with ribonuclease S-protein. With 12-fold excess of the peptide, the complex exhibited 36% of the specific activity of fully native ribonuclease S against the substrate cyclic cytidine 2':3'-monophosphate at pH 7.15. The dissociation constant of the model peptide for S-protein was found to be 1.1 x 10(-6) M, compared with 0.1 x 10(-6) M for native S-peptide. Crystals grown of the model peptide-S-protein complex were found to be isomorphous with those of native complex. The activity, stability, and structural integrity of the model complex verify the deductions made about essential sequence information in the NH2-terminal region of ribonuclease. Further, the results emphasize the general usefulness of the conformational approach in designing simplified sequences for other peptides and proteins.
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PMID:Sequence modeling using semisynthetic ribonuclease S. 627 8


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