scholarly journals Re-activation of the peptidyltransferase centre of rabbit reticulocyte ribosomes after inactivation by exposure to low concentrations of magnesium ion

1976 ◽  
Vol 160 (3) ◽  
pp. 521-531 ◽  
Author(s):  
R A Cox ◽  
P Greenwell ◽  
W Hirst
Keyword(s):  
Conformational Change ◽  
Gel Electrophoresis ◽  
Supernatant Fraction ◽  
Magnesium Ion ◽  
Differential Centrifugation ◽  
Base Pairs ◽  
Low Concentrations ◽  
Mgcl2 Concentration ◽  
Protein Moiety ◽  
Rabbit Reticulocytes

1. The larger subrivosomal particles of rabbit reticulocytes retained full activity in the puromycin reaction and in poly(U)-directed polyphenylalanine synthesis after 4h at 0° C when buffered 0.5M-NH4Cl/10-30mM-MgCl2 was the solvent. 2. Activity in the puromycin reaction was diminished to approx 10% after 15-30 min at 0° C when the concentration of MgCl2 was lowered to 2mM. 3. Activity was not restored when the concentration of MgCl2 was raised from 2mM to 10-30 mM at 0° C. However, activity was recovered as measured by both assay systems when the ribosome fraction was heated to 37° C at the higher concentrations of MgCl2. 4. Recovery of activity was noted during the course of the polyphenylalanine synthesis in 50 mM-KCl/5mM-MgCl2/25mM-Tris/HCl, pH 7.6, at 37° C. Re-activation was slow at 20° C and below. 5. No more than about 5% of the protein moiety of the subparticle was lost in 0.5M-NH4Cl on decreasing MgCl2 concentration from 10mM to 2mM. No proteins were detected in the supernatant fractions by gel electrophoresis after ribosomes were separated by differential centrifugation. The supernatant fraction was not essential for the recovery of activity. However, at higher (e.g. 1M) concentrations of NH4Cl, proteins were split from the subparticle. 6. The loss and regain of activity found on lowering and restoring the concentration of MgCl2 at 0.5M-NH4Cl appears to arise from a conformational change that does not seem to be associated with a loss and regain of particular proteins. 7. A 2% decrease in E260 was noticed when the concentration of Mg2+ was restored, and the change in the spectrum indicated a net increase of approx. 100A-U base-pairs per subribosomal particle. 8. When the concentration of Mg2+ was restored, s20,w of the subparticle remained at 52± 1S until the sample was incubated at 37° C when s20,w increased to 56 ± 1S compared with the value of 58 ± 1S for the subparticle as originally isolated.

scholarly journals Detection of G1 proteins in Chinese hamster cells synchronized by isoleucine deprivation or mitotic selection.

1975 ◽  
Vol 66 (1) ◽  
pp. 95-101 ◽  
Author(s):  
K D Ley
Keyword(s):  
Time Course ◽  
Sodium Dodecyl ◽  
Chinese Hamster ◽  
Protein S ◽  
S Phase ◽  
Supernatant Fraction ◽  
G1 Phase ◽  
Differential Centrifugation ◽  
Chinese Hamster Cells ◽  
Soluble Supernatant

Examination of labeling patterns of proteins in Chinese hamster cells(line CHO) revealed the presence of a class of protein(s) that is synthesized during G1 phase of the cell cycle. Cells arrested in G1 by isoleucine (Ile) deprivation were prelabeded with [14-C]Ile, induced to traverse G1 by addition of unlabeled Ile, and labeled with [3-H]Ile at hourly intervals. Cells were fractionated into neclear and cytoplasmic portions, and proteins were separated by sodium dodecyl sulfate-polyacrylamide get electrophoresis. Gel profiles of proteins in the 45,000-160,000 mol wt range from the cytoplasm of cells in G1 were similar to those from cells arrested in G1 except for the presence of a mojor peak of [1-H]Ile incorporated into a protein(s) of approximately 80,000 mol wt. Peaks of net [3-H]Ile incorporation were not detected in neclear preparations. Cellular fractionation by differential centrifugation showed the peak I protein was located in the soluble supernatant fraction of the cytoplasm. Time-course studies showed that synthesis of this protein began 1-2 h after initiation of G1 traverse; the protein reached maximum levels in 4-6 h and was reduced to undetectable levels by 9 h. A cytoplasmic protein with similar electrophoretic mobility was found in G1 phase of cells synchronized by mitotic selection. This class of proteins is synthesized by cells before entry into S phase and may be involved in initiation of DNA synthesis.

The isolation of surface array proteins from bacteria

1984 ◽  
Vol 62 (11) ◽  
pp. 1181-1189 ◽  
Author(s):  
S. F. Koval ◽  
R. G. E. Murray
Keyword(s):  
Molecular Weight ◽  
Protein Conformation ◽  
Gel Electrophoresis ◽  
Guanidine Hydrochloride ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Structural Features ◽  
Proteolytic Degradation ◽  
Low Concentrations ◽  
Single Polypeptide

The methods used for the isolation of regularly structured (RS) surface array proteins of a range of prokaryotes are described. Most RS proteins can be selectively solubilized from envelope preparations with low concentrations of urea or guanidine hydrochloride. Sodium dodecyl sulfate – polyacrylamide gel electrophoresis analysis of the protein extracts shows that most RS arrays are composed of a single polypeptide that may contain carbohydrate. The molecular weight of the proteins varies from 41 000 to 200 000. Possible reasons for the presence of more than one polypeptide in RS protein preparations are discussed, as well as the evidence for proteolytic degradation of some RS proteins during isolation. Structural features of the RS proteins are described and the importance of protein conformation to assembly of the arrays is indicated.

scholarly journals Conformational changes at the active site of creatine kinase at low concentrations of guanidinium chloride

1993 ◽  
Vol 291 (1) ◽  
pp. 103-107 ◽  
Author(s):  
H M Zhou ◽  
X H Zhang ◽  
Y Yin ◽  
C L Tsou
Keyword(s):  
Creatine Kinase ◽  
Fluorescent Probe ◽  
Conformational Change ◽  
Conformational Changes ◽  
Active Site ◽  
Emission Intensity ◽  
Enzyme Inactivation ◽  
Amino Groups ◽  
Guanidinium Chloride ◽  
Low Concentrations

It has been previously reported that, during denaturation of creatine kinase by guanidinium chloride (GdmCl) or urea [Tsou (1986), Trends Biochem. Sci. 11, 427-429], inactivation occurs before noticeable conformational change can be detected, and it is suggested that the conformation at the active site is more easily perturbed and hence more flexible than the molecule as a whole. In this study, the thiol and amino groups at or near the active site of creatine kinase are labelled with o-phthalaldehyde to form a fluorescent probe. Both the emission intensity and anisotropy decrease during denaturation indicating exposure of this probe and increased mobility of the active site. The above conformational changes take place together with enzyme inactivation at lower GdmCl concentrations than required to bring about intrinsic fluorescence changes of the enzyme. At the same GdmCl concentration, the rate of exposure of the probe is comparable with that of inactivation and is several orders of magnitude faster than that for the unfolding of the molecule as a whole.

scholarly journals Different molecular forms of plasminogen and plasmin produced by urokinase in human plasma and their relation to protease inhibitors and lysis of fibrinogen and fibrin

1974 ◽  
Vol 143 (2) ◽  
pp. 273-283 ◽  
Author(s):  
Sten Müllertz
Keyword(s):  
Human Plasma ◽  
Protease Inhibitors ◽  
Gel Electrophoresis ◽  
Protease Activity ◽  
Gel Filtration ◽  
Molecular Forms ◽  
Crossed Immunoelectrophoresis ◽  
Low Concentrations ◽  
Α2 Macroglobulin ◽  
Esterase Inhibitor

Urokinase-activated human plasma was studied by gel electrophoresis, gel filtration, crossed immunoelectrophoresis and electroimmunoassay with specific antibodies and by assay of esterase and protease activity of isolated fractions. Urokinase induced the formation of different components with plasminogen+plasmin antigenicity. At low concentrations of urokinase, a component with a KD value of 0.18 by gel filtration and post β1 mobility by gel electrophoresis was detected. The isolated component had no enzyme or plasminogen activity. In this plasma sample fibrinogen was not degraded for 10h, but when fibrin was formed, by addition of thrombin, fibrin was quickly lysed, and simultaneously a component with a KD value of 0 and α2 mobility appeared, which was probably plasmin in a complex with α2 macroglobulin. This complex showed both esterase and protease activity. After gel filtration with lysine buffer of the clotted and lysed plasma another two components were observed with about the same KD value by gel filtration as plasminogen (0.35), but β1 and γ mobilities by gel electrophoresis. They appeared to be modified plasminogen molecules, and possibly plasmin with γ mobility. Similar processes occurred without fibrin at higher urokinase concentrations. Here a relatively slow degradation of fibrinogen was correlated to the appearance of the plasmin–α2 macroglobulin complex. The fibrin surface appeared to catalyse the ultimate production of active plasmin with a subsequent preferential degradation of fibrin and the formation of a plasmin–α2 macroglobulin complex. The gel filtration and electrophoresis of the plasma protease inhibitors, α1 antitrypsin, inter-α-inhibitor, antithrombin III, and C1-esterase inhibitor indicated that any complex between plasmin and these inhibitors was completely dissociated. The β1 and post β1 components appear to lack correlates among components occurring in purified preparations of plasminogen and plasmin.

scholarly journals Coproporphyrinogenase in tobacco (Nicotiana tabacum L.)

1970 ◽  
Vol 117 (2) ◽  
pp. 215-220 ◽  
Author(s):  
W. P. Hsu ◽  
G. W. Miller
Keyword(s):  
Enzyme Activity ◽  
Nicotiana Tabacum ◽  
Differential Centrifugation ◽  
Enzyme Protein ◽  
Sodium Amalgam ◽  
Low Concentrations ◽  
Nicotiana Tabacum L ◽  
Km Value ◽  
Ammonium Sulphate Fractionation ◽  
Final Purification

1. Coproporphyrinogenase was extracted and purified from tobacco (Nicotiana tabacum L.). Enzyme activity was mainly located in mitochondria rather than in chloroplasts. The enzyme was purified by differential centrifugation, ammonium sulphate fractionation, calcium phosphate gel adsorption and dialysis. A 69-fold final purification was obtained. 2. An apparent Km value of 3.6×10−5m was found, the value being largely dependent on the amount of coproporphyrin III recovered after reduction with sodium amalgam to coproporphyrinogen III. Protoporphyrin formation was linear up to 3h and decreased with further incubation. The enzyme activity increased with the concentration of enzyme protein up to 30μg/ml of solution. 3. Enzyme activity was greatly enhanced by increasing Fe2+ concentrations up to 0.5mm, beyond which inhibition occurred. Co2+ and Mn2+ were also found to activate at low concentrations (0.1mm) and inhibit at higher concentrations (5mm). Fe3+ and Cu2+, both at 0.1mm, and o-phenanthroline and EDTA, each at 1mm, were found to be inhibitory.

VARIAN NON-DELESI 9 PASANG BASA DNA MITOKONDRIA MANUSIA SAMPEL FORENSIK BALI

2005 ◽  
Vol 6 (1) ◽  
pp. 74
Author(s):  
Gun Gun Gumilar ◽  
A. Saifuddin Noer
Keyword(s):  
Gel Electrophoresis ◽  
Secondary Data ◽  
Primary Data ◽  
Agarose Gel Electrophoresis ◽  
Chain Reaction ◽  
Base Pairs ◽  
Human Mitochondrial Dna ◽  
Deletion Variant ◽  
Forensic Samples ◽  
Polymerase Chain

One of human mitochondrial DNA (mtDNA) variant is a 9 base pairs (bp) deletion in the COII/tRNALys intergenic region. In construction mtDNA nomenclature, 9-bp deletion database consist of primary and secondary data is needed, including Bali bombing forensic samples. Here we report a 9-bp non- deletion mtDNA variant from Bali bombing forensic samples to complete primary data. Polymerase Chain Reaction (PCR) technique with 2 set primer was used to detect 9-bp deletion. The PCR result was detected by agarose gel electrophoresis, which showed two bands (0.1 and 0.4 kb) for non-deletion variant control, and one band (0.4 kb) for deletion variant control. If the sample has 9-bp deletion, only one of the primer pairs could amplify a fragment of 0.4 kb. If the sample does not have 9-bp deletion, the other primer pair will amplify a 0.1 kb product. The result showed that none of the 24 samples has 9-bp deletion. These results are contributed to the human mtDNA database and nomenclature construction. Keywords: mtDNA, 9-bp deletion, PCR

scholarly journals DNA polymerase β: effects of gapped DNA substrates on dNTP specificity, fidelity, processivity and conformational changes1

1998 ◽  
Vol 331 (1) ◽  
pp. 79-87 ◽  
Author(s):  
Jinwoo AHN ◽  
Vadim S. KRAYNOV ◽  
Xuejun ZHONG ◽  
Brian G. WERNEBURG ◽  
Ming-Daw TSAI
Keyword(s):  
Conformational Change ◽  
Dna Polymerase ◽  
Catalytic Efficiency ◽  
Duplex Dna ◽  
Gap Filling ◽  
Dna Polymerase Β ◽  
Base Pairs ◽  
Single Nucleotide ◽  
Dna Substrates ◽  
Gapped Dna

Pre-steady-state kinetic analysis was used to compare the catalytic properties of DNA polymerase β (Pol β) for single-base gap-filling and regular duplex DNA synthesis. The rate of polymerization (kpol) and the apparent equilibrium dissociation constant of dNTP (Kd) were determined with single-nucleotide gapped DNA substrates for all four possible correct base pairs and twelve possible incorrect base pairs, and the results were compared with those obtained previously with non-gapped primer/template duplex DNA substrates. For correct dNTP incorporation, the use of single-nucleotide gapped DNA led to significant decreases in the Kd of dNTP. Although kpol was little affected, the catalytic efficiency kpol/Kd increased significantly owing to the decreases in Kd. In contrast, for incorrect dNTP incorporation, the use of single-nucleotide gapped DNA substrates did not affect the Kd of dNTP appreciably but caused the kpol (and thus kpol/Kd) for incorrect dNTP incorporation to increase. As a consequence the fidelity of Pol β was not significantly affected by the use of single-nucleotide gapped DNA substrates. In addition we show that under processive polymerization conditions the processivity of Pol β increases in the gap-filling synthesis owing to a decreased rate of DNA dissociation. Finally, with a single-nucleotide gapped DNA substrate the rate-limiting conformational change step before chemistry was also observed. However, the preceding fast conformational change observed with duplex DNA substrates was not clearly detected. A possible cause is that in the complex with the gapped DNA, the 8 kDa N-terminal domain of Pol β already exists in a closed conformation. This interpretation was supported by tryptic digestion experiments.

Assignment of Imino Proton Signals of G-C Base Pairs and Magnesium Ion Binding: An NMR Study of Bovine Mitochondrial tRNASerGCU Lacking the Entire D Arm

1997 ◽  
Vol 121 (6) ◽  
pp. 1115-1122 ◽  
Author(s):  
I. Hayashi ◽  
T. Yokogawa ◽  
G. Kawai ◽  
T. Ueda ◽  
K. Nishikawa ◽  
...  
Keyword(s):  
Magnesium Ion ◽  
Ion Binding ◽  
Base Pairs ◽  
Imino Proton ◽  
Nmr Study

scholarly journals Partial isolation and translation in vitro of messenger ribonucleic acid for phosphoenolpyruvate carboxykinase (guanosine triphosphate)

1976 ◽  
Vol 156 (3) ◽  
pp. 619-626 ◽  
Author(s):  
S M Tilghman ◽  
L M Fisher ◽  
L Reshef ◽  
F J Ballard ◽  
R W Hanson
Keyword(s):  
Gel Electrophoresis ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Gradient Centrifugation ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Messenger Ribonucleic Acid ◽  
Partial Isolation ◽  
Heterologous Cell ◽  
Rabbit Reticulocytes

1. mRNA was extracted from the livers of starved rats and incubated in a heterologous cell-free protein-synthesizing system derived from rabbit reticulocytes. The presence of newly synthesized phosphoenolpyruvate carboxykinase (GTP) was detected by immunoprecipitation with a specific antibody to the enzyme and analysis by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 2. The synthesis of the enzyme was dependent on the addition of rat liver RNA, whereas RNA isolated from rat spleen was inactive. If ovalbumin and anti-ovalbumin were used to form the immunoprecipitates, no radioactivity that migrated as phosphoenolpyruvate carboxykinase was detected. 3. The optimal concentrations of magnesium acetate and KCl for phosphoenolpyruvate carboxykinase synthesis were determined. 4. When polyribosomal RNA was separated by sucrose-gradient centrifugation, phosphoenolpyruvate carboxykinase mRNA migrated between 20 and 26 S in keeping with the high mol. wt. of the protein (85 000). 5. The presence of poly(A) in phosphoenolpyruvate carboxykinase mRNA was suggested by retention of mRNA activity on oligo(dT)-cellulose columns. 6. It was concluded that the cell-free synthesis of phosphoenolpyruvate carboxykinase can serve as a bioassay for intracellular phosphoenolpyruvate carboxykinase mRNA.

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