Characterization of modified myosin at low ionic strength. Enzymic and spin-label studies

Biochemistry ◽  
1973 ◽  
Vol 12 (21) ◽  
pp. 4206-4211 ◽  
Author(s):  
Deborah Bennett Stone ◽  
Shirley C. Prevost
Keyword(s):  
Ionic Strength ◽  
Spin Label ◽  
Low Ionic Strength

Characterization of genomic poly(dT-dG).poly(dC-dA) sequences: structure, organization, and conformation

1984 ◽  
Vol 4 (12) ◽  
pp. 2610-2621
Author(s):  
H Hamada ◽  
M G Petrino ◽  
T Kakunaga ◽  
M Seidman ◽  
B D Stollar
Keyword(s):  
Ionic Strength ◽  
Inverted Repeats ◽  
Actin Gene ◽  
Base Pairs ◽  
S1 Nuclease ◽  
Coding Sequences ◽  
Supercoiled Plasmid ◽  
Marked Preference ◽  
Low Ionic Strength

Hybridization studies suggest the abundant presence of poly(dT-dG).poly(dC-dA) (TG-element), a potential Z-DNA sequence, in eucaryotic genomes. We have isolated and characterized TG-elements from different locations in the human genome: from randomly isolated clones, associated with the actin gene family, and linked to another repeated element. The results indicate that the following features are typical of these TG-elements: the elements consist of 20 to 60 base pairs of (dT-dG)n.(dC-dA)n, the sequences characterized in our study were not flanked by direct or inverted repeats, the sequences are interspersed rather than in satellite blocks, the elements are not usually associated with other repeated elements, and some of the elements are found near coding sequences or in introns. Studies on the conformation of a genomic TG-element in a supercoiled plasmid indicate several distinct properties of the TG-element: it is in the Z-form only at low ionic strength, S1 nuclease recognizes its Z-form with a marked preference for one of the B-Z junctions, and the sensitive region extends for 20 base pairs near the B-Z junction. In contrast to the result with the supercoiled plasmid, S1 nuclease failed to recognize the TG-element in minichromosomes.

scholarly journals Electrophorus acetylcholinesterase. Biochemical and electron microscope characterization of low ionic strength aggregates

1978 ◽  
Vol 77 (2) ◽  
pp. 315-322 ◽  
Author(s):  
J Cartaud ◽  
S Bon ◽  
J Massoulié
Keyword(s):  
Ionic Strength ◽  
High Resolution Electron Microscopy ◽  
Hydrodynamic Characteristics ◽  
Sedimentation Analysis ◽  
The Core ◽  
Resolution Electron ◽  
Electric Eel ◽  
Oxygen Oxidation ◽  
Low Ionic Strength

The "tailed" molecules of Electrophorus (electric eel) acetylcholinesterase aggregate under conditions of low ionic strength. These aggregates have been studied by sedimentation analysis and high-resolution electron microscopy. They consist of bundles of at least half a dozen molecules, the tails of which are packed side by side, to form the core of the structure. Although aggregation is normally fully reversible, aggregates were irreversibly stabilized by methylene blue-sensitized photo-oxidation. This process was shown to consist of a singlet oxygen oxidation reaction and probably involves methionine or histidine residues. It did not modify the structural or hydrodynamic characteristics of the aggregates.

Selection and characterization of DNAzymes with synthetically appended functionalities: A case of a synthetic RNAsea mimic

2004 ◽  
Vol 76 (7-8) ◽  
pp. 1571-1577 ◽  
Author(s):  
R. Ting ◽  
Leonard Lermer ◽  
J. Thomas ◽  
Y. Roupioz ◽  
D. M. Perrin
Keyword(s):  
Ionic Strength ◽  
Nucleic Acids ◽  
Rate Constants ◽  
Complex Chemical ◽  
Low Ionic Strength ◽  
Low Rate ◽  
Selection Of

We have been interested in merging synthetic nucleotide chemistry with combinatorial selection of DNAzymes to deliver a more complete (and complex) chemical complement to the catalytic repertoire of nucleic acids. Thus we ask, what do modified dNTPs really bring to nucleic acids in terms of an increased repertoire? In asking this question, we have looked first at conditions, and more recently for reaction classes where nucleic acids are found to be catalytically inefficient, deficient, or at least to date, seemingly incapable of certain functions. A case of this is M2+-independent ribophosphodiester hydrolysis at physiological pH and low ionic strength where nucleic acids exhibit especially low rate constants for self-cleavage and seem to be incapable of turnover.

scholarly journals Characterization of genomic poly(dT-dG).poly(dC-dA) sequences: structure, organization, and conformation.

1984 ◽  
Vol 4 (12) ◽  
pp. 2610-2621 ◽  
Author(s):  
H Hamada ◽  
M G Petrino ◽  
T Kakunaga ◽  
M Seidman ◽  
B D Stollar
Keyword(s):  
Ionic Strength ◽  
Inverted Repeats ◽  
Actin Gene ◽  
Base Pairs ◽  
S1 Nuclease ◽  
Coding Sequences ◽  
Supercoiled Plasmid ◽  
Marked Preference ◽  
Low Ionic Strength

Hybridization studies suggest the abundant presence of poly(dT-dG).poly(dC-dA) (TG-element), a potential Z-DNA sequence, in eucaryotic genomes. We have isolated and characterized TG-elements from different locations in the human genome: from randomly isolated clones, associated with the actin gene family, and linked to another repeated element. The results indicate that the following features are typical of these TG-elements: the elements consist of 20 to 60 base pairs of (dT-dG)n.(dC-dA)n, the sequences characterized in our study were not flanked by direct or inverted repeats, the sequences are interspersed rather than in satellite blocks, the elements are not usually associated with other repeated elements, and some of the elements are found near coding sequences or in introns. Studies on the conformation of a genomic TG-element in a supercoiled plasmid indicate several distinct properties of the TG-element: it is in the Z-form only at low ionic strength, S1 nuclease recognizes its Z-form with a marked preference for one of the B-Z junctions, and the sensitive region extends for 20 base pairs near the B-Z junction. In contrast to the result with the supercoiled plasmid, S1 nuclease failed to recognize the TG-element in minichromosomes.

Conformational Transitions in Escherichia coli Ribosomal RNAs as Visualized by Dedicated STEM

1988 ◽  
Vol 46 ◽  
pp. 176-177
Author(s):  
J.S. Wall ◽  
V. Maridiyan ◽  
S. Tumminia ◽  
J. Hairifeld ◽  
M. Boublik
Keyword(s):  
Ionic Strength ◽  
Three Dimensional ◽  
Conformational Transitions ◽  
Dark Field ◽  
Dimensional Structure ◽  
Ribosomal Rnas ◽  
Field Mode ◽  
Freeze Dried ◽  
High Resolution Images ◽  
Low Ionic Strength

The high contrast in the dark-field mode of dedicated STEM, specimen deposition by the wet film technique and low radiation dose (1 e/Å2) at -160°C make it possible to obtain high resolution images of unstained freeze-dried macromolecules with minimal structural distortion. Since the image intensity is directly related to the local projected mass of the specimen it became feasible to determine the molecular mass and mass distribution within individual macromolecules and from these data to calculate the linear density (M/L) and the radii of gyration.2 This parameter (RQ), reflecting the three-dimensional structure of the macromolecular particles in solution, has been applied to monitor the conformational transitions in E. coli 16S and 23S ribosomal RNAs in solutions of various ionic strength.In spite of the differences in mass (550 kD and 1050 kD, respectively), both 16S and 23S RNA appear equally sensitive to changes in buffer conditions. In deionized water or conditions of extremely low ionic strength both appear as filamentous structures (Fig. la and 2a, respectively) possessing a major backbone with protruding branches which are more frequent and more complex in 23S RNA (Fig. 2a).

An Evaluation of a Plasma Fractionation System

1960 ◽  
Vol 4 (01) ◽  
pp. 031-044
Author(s):  
George Y. Shinowara ◽  
E. Mary Ruth
Keyword(s):  
Biological Activity ◽  
Ionic Strength ◽  
Plasma Proteins ◽  
High Concentration ◽  
Significant Evidence ◽  
Native Proteins ◽  
Mobility Data ◽  
Fractionation Procedure ◽  
The Individual ◽  
Low Ionic Strength

SummaryFour primary fractions comprising at least 97 per cent of the plasma proteins have been critically appraised for evidence of denaturation arising from a low temperature—low ionic strength fractionation system. The results in addition to those referable to the recovery of mass and biological activity include the following: The high solubilities of these fractions at pH 7.3 and low ionic strengths; the compatibility of the electrophoretic and ultracentrifugal data of the individual fractions with those of the original plasma; and the recovery of hemoglobin, not hematin, in fraction III obtained from specimens contaminated with this pigment. However, the most significant evidence for minimum alterations of native proteins was that the S20, w and the electrophoretic mobility data on the physically recombined fractions were identical to those found on whole plasma.The fractionation procedure examined here quantitatively isolates fibrinogen, prothrombin and antithrombin in primary fractions. Results have been obtained demonstrating its significance in other biological systems. These include the following: The finding of 5 S20, w classes in the 4 primary fractions; the occurrence of more than 90 per cent of the plasma gamma globulins in fraction III; the 98 per cent pure albumin in fraction IV; and, finally, the high concentration of beta lipoproteins in fraction II.

scholarly journals A novel procedure for the rapid purification of plastocyanin from pea (Pisum sativum) leaves

1981 ◽  
Vol 193 (1) ◽  
pp. 375-378 ◽  
Author(s):  
A R Ashton ◽  
L E Anderson
Keyword(s):  
Ionic Strength ◽  
Pisum Sativum ◽  
Deae Cellulose ◽  
High Concentrations ◽  
Rapid Purification ◽  
Low Ionic Strength

Plastocyanin is soluble at high concentrations (greater than 3 M) of (NH4)2SO4 but under these conditions will adsorb tightly to unsubstituted Sepharose beads. This observation was utilized to purify plastocyanin from pea (Pisum sativum) in two chromatographic steps. Sepharose-bound plastocyanin was eluted with low-ionic-strength buffer and subsequently purified to homogeneity by DEAE-cellulose chromatography.

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