scholarly journals The behaviour of heterogeneous nuclear ribonucleic acid in partially and completely denaturing conditions

1974 ◽  
Vol 141 (2) ◽  
pp. 477-484 ◽  
Author(s):  
Michael E. Bramwell
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
High Temperatures ◽  
Sedimentation Rate ◽  
Ribonucleic Acid ◽  
28S Rrna ◽  
Nuclear Rna ◽  
Step Down ◽  
Low Ionic Strength ◽  
Nucleolar Rna

It is shown that the heterogeneous nuclear RNA (HnRNA) synthesized in the presence of actinomycin and at low and high temperatures sediments in low-ionic-strength sucrose gradients between the rRNA components, similar to the unmethylated RNA synthesized under ‘step-down’ conditions. If the ionic strength is increased then the HnRNA sediments more rapidly than 28S rRNA, with a large proportion about the 45S precursor rRNA position. Initially this was thought to be due to aggregation of the HnRNA; however, centrifugation and electrophoresis in completely denaturing conditions suggest that the molecular weight of this species of RNA is very large The experiments reveal that HnRNA is conformationally unstable relative to the nucleolar RNA and that the slower sedimentation rate of HnRNA in 5mm-EDTA–Tris base–sucrose gradients reflects the greater expansion of the HnRNA relative to the nucleolar RNA. The implications of this finding are discussed.

Intranuclear Accumulation of Rna Resembling the Smaller Ribosomal Rna Component

1970 ◽  
Vol 6 (1) ◽  
pp. 53-72
Author(s):  
M. E. BRAMWELL
Keyword(s):  
Ribosomal Rna ◽  
Base Composition ◽  
Actinomycin D ◽  
Total Radioactivity ◽  
16S Ribosomal Rna ◽  
Low Concentrations ◽  
Rapid Accumulation ◽  
Nuclear Rna ◽  
Step Down ◽  
Nucleolar Rna

A study was made of the nuclear RNA in HeLa cells with particular reference to the rapidly labelled fractions. It was found that if cells were incubated at a high density, that is, under ‘step-down’ conditions, there was a rapid accumulation of RNA in the nucleus. The fraction of the nuclear RNA which includes rapidly labelled RNA and which binds tightly to columns of methylated albumin on kieselguhr increased in amount and reached levels which permitted enough of the material to be isolated for direct measurement of its base composition. This was found to be very similar to that of 16s ribosomal RNA. When cells growing logarithmically were treated with low concentrations of actinomycin D and then incubated in the presence of [3H]uridine it was found that an RNA fraction which bound tightly to methylated albumin on kieselguhr again accumulated in the nucleus. This fraction resembled that which accumulated under ‘step-down’ conditions. It contained over 85% of the total radioactivity in the nuclear RNA and again had a base composition very similar to 16s ribosomal RNA. Since nucleolar RNA synthesis was inhibited by the concentrations of actinomycin D used, it appeared that an RNA closely resembling 16s ribosomal RNA was synthesized outside the nucleolus. Sedimentation patterns on sucrose density gradients and thermal denaturation profiles lent support to the view that the RNA which binds tightly to columns of methylated albumin on kieselguhr probably represents ‘nascent’ 16s ribosomal RNA.

scholarly journals Protein diffusion through charged nanopores with different radii at low ionic strength

2014 ◽  
Vol 16 (39) ◽  
pp. 21570-21576 ◽  
Author(s):  
Pieter Stroeve ◽  
Masoud Rahman ◽  
Lekkala Dev Naidu ◽  
Gilbert Chu ◽  
Morteza Mahmoudi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Protein Diffusion ◽  
Similar Molecular Weight ◽  
Low Ionic Strength ◽  
Charged Membranes ◽  
Pore Permeability

Pore permeability for two similar molecular weight proteins (BSA and BHb) through nanoporous charged membranes at low ionic strength (I = 0.001 M).

scholarly journals The presence of a high-molecular-weight (guanine-plus-cytosine)-rich segment at the 3' end of rabbit 28S ribosomal ribonucleic acid.

1975 ◽  
Vol 147 (3) ◽  
pp. 625-628 ◽  
Author(s):  
A A Hadjiolov ◽  
R A Cox ◽  
P Huvos
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ribonucleic Acid ◽  
Average Molecular Weight ◽  
28S Rrna ◽  
Number Average Molecular Weight ◽  
Ribonuclease T1 ◽  
Naphthoic Acid ◽  
Rrna Molecule ◽  
Ribosomal Ribonucleic Acid

The 3′ hydroxyl end of 28S L-rRNA (major RNA species of the larger subribosomal particle) was labelled by coupling its 2-hydroxy-3-naphthoic acid hydrazine with diazotized [3H]aniline. The RNA was hydrolysed partially with ribonuclease T1 and fractionated on Sephadex G-200. The results show that a highly structured segment with 78% G+C content and a number-average molecular weight of at least 1.0×10(5)-1.8×10(5) is located at the 3′ hydroxyl end of the 28S rRNA molecule.

Human and Bovine Plasminogen-Free Thrombin, Purified by Means of Gel Filtration and Ion Exchange Chromatography

1966 ◽  
Vol 15 (03/04) ◽  
pp. 501-510 ◽  
Author(s):  
W Berg ◽  
K Korsan-Bengtsen ◽  
J Ygge
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Large Scale ◽  
Gel Filtration ◽  
Trisodium Citrate ◽  
Exchange Chromatography ◽  
Simple Method ◽  
Commercial Preparation ◽  
Usual Manner ◽  
Low Ionic Strength

SummaryA simple method for preparation of plasminogen-free human and bovine thrombin is described.Crude thrombin was prepared in the usual manner from oxalated plasma by means of adsorption on BaSO4, elution with trisodium citrate and activating the eluate from BaSO4 with tissue thromboplastin.This crude thrombin was purified by means of gel-filtration and chromatography on CM-Sephadex A-50.The gel-filtration was performed on three types of Sephadex, G-75, G-50, and G--25. By means of Sephadex G-75 the thrombin was well separated from the main part of inert protein and this type of Sephadex was used for the purification in large-scale. Separation of thrombin from protein of higher molecular weight was also obtained with Sephadex G-50 but not with Sephadex G-25 indicating a molecular weight of thrombin between 4000 and 10,000.The importance of using an elution buffer of sufficient high ionic strength for gel-filtration is shown. A great deal of the thrombin was adsorbed to the Sephadex if the gel-filtration was performed at a too low ionic strength.The final preparation contained 30,000 NIH units of thrombin per mg tyrosin and no detectable plasminogen.The commercial preparation “Topostasine” was also purified in the same manner, but the plasminogen content in “Topostasine” was high and could not be completely separated from thrombin.

scholarly journals Production and characterisation of a marine Halomonas surface-active exopolymer

2019 ◽  
Vol 104 (3) ◽  
pp. 1063-1076
Author(s):  
Tony Gutierrez ◽  
Gordon Morris ◽  
Dave Ellis ◽  
Barbara Mulloy ◽  
Michael D. Aitken
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
High Molecular Weight ◽  
Positive Influence ◽  
Contaminated Sites ◽  
Crude Oils ◽  
Magnetic Resonance Spectroscopic Analysis ◽  
Surface Active ◽  
Low Ionic Strength ◽  
Pure Hydrocarbon

AbstractDuring screening for novel emulsifiers and surfactants, a marine gammaproteobacterium, Halomonas sp. MCTG39a, was isolated and selected for its production of an extracellular emulsifying agent, P39a. This polymer was produced by the new isolate during growth in a modified Zobell’s 2216 medium amended with 1% glucose, and was extractable by cold ethanol precipitation. Chemical, chromatographic and nuclear magnetic resonance spectroscopic analysis confirmed P39a to be a high-molecular-weight (~ 261,000 g/mol) glycoprotein composed of carbohydrate (17.2%) and protein (36.4%). The polymer exhibited high emulsifying activities against a range of oil substrates that included straight-chain aliphatics, mono- and alkyl- aromatics and cycloparaffins. In general, higher emulsification values were measured under low (0.1 M PBS) compared to high (synthetic seawater) ionic strength conditions, indicating that low ionic strength is more favourable for emulsification by the P39a polymer. However, as observed with other bacterial emulsifying agents, the polymer emulsified some aromatic hydrocarbon species, as well as refined and crude oils, more effectively under high ionic strength conditions, which we posit could be due to steric adsorption to these substrates as may be conferred by the protein fraction of the polymer. Furthermore, the polymer effected a positive influence on the degradation of phenanthrene by other marine bacteria, such as the specialist PAH-degrader Polycyclovorans algicola. Collectively, based on the ability of this Halomonas high-molecular-weight glycoprotein to emulsify a range of pure hydrocarbon species, as well as refined and crude oils, it shows promise for the bioremediation of contaminated sites.

Properties and characteristics of a bacteriocin-like substance produced by Propionibacterium acnes isolated from dental plaque

1988 ◽  
Vol 34 (12) ◽  
pp. 1344-1347 ◽  
Author(s):  
Greg E. Paul ◽  
S. James Booth
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Dental Plaque ◽  
Propionibacterium Acnes ◽  
Gram Positive ◽  
Gram Negative ◽  
A Cell ◽  
Approximate Molecular Weight ◽  
Low Ionic Strength

A cell-associated bacteriocinlike substance with an approximate molecular weight of 78 000 was isolated from an oral isolate of Propionibacterium acnes. The substance was bacteriostatic and was active against both gram-positive and gram-negative anaerobes. Lysozyme inhibited the activity of the bacteriocinlike substance at low ionic strength.

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