Concentration Dependence of Sedimentation Coefficient of Deoxyribonucleic Acid with added Sodium Chloride

Nature ◽  
1962 ◽  
Vol 196 (4860) ◽  
pp. 1201-1203 ◽  
Author(s):  
PRASANTA K. GANGULI ◽  
AMRITA L. BHATTACHARYYA
Keyword(s):  
Sodium Chloride ◽  
Concentration Dependence ◽  
Deoxyribonucleic Acid ◽  
Sedimentation Coefficient

COMPLEX FORMATION BETWEEN BASIC ANTIBIOTICS AND DEOXYRIBONUCLEIC ACID IN HUMAN PULMONARY SECRETIONS

PEDIATRICS ◽  
1965 ◽  
Vol 36 (5) ◽  
pp. 714-720
Author(s):  
Joseph L. Potter ◽  
LeRoy W. Matthews ◽  
Samuel Spector ◽  
Joy Lemm
Keyword(s):  
Cystic Fibrosis ◽  
Sodium Chloride ◽  
Complex Formation ◽  
Chain Length ◽  
Deoxyribonucleic Acid ◽  
Antimicrobial Agents ◽  
Dnase I ◽  
Two Samples

1. Complex formation and precipitation of DNA by neomycin, with consequent inactivation of the antibiotic, has been shown to occur in the pulmonary secretions of patients with cystic fibrosis. 2. Highly polymerized DNA from a variety of sources, as well as two samples of RNA, were precipitated by neomycin in vitro. Polymixin, kanamycin, colymycin, and streptomycin similarly co-precipitate with DNA in vitro. 3. The minimum chain length of polynucleotide required for precipitation in the DNA-neomycin system was 10. 4. The complex is readily attacked by DNase I resulting in the splitting of the DNA and the liberation of the antibiotic. Both components of the complex are solubilized in M sodium chloride. 5. The resistance of purulent foci of infection to therapy with basic antimicrobial agents may, in part, be due to the complex formation with the high levels of DNA found at the site of infection.

scholarly journals Ultracentrifuge studies of histone fractions from calf thymus deoxyribonucleoprotein

1969 ◽  
Vol 114 (2) ◽  
pp. 227-235 ◽  
Author(s):  
P A Edwards ◽  
K V Shooter
Keyword(s):  
Sodium Chloride ◽  
Guanidine Hydrochloride ◽  
Chloride Concentration ◽  
Sedimentation Coefficient ◽  
Apparent Molecular Weight ◽  
Concentrated Solutions ◽  
Molecular Weights ◽  
Sodium Chloride Solutions ◽  
Low Concentrations ◽  
Calf Thymus

Molecular weights and sedimentation coefficients of four major fractions of calf thymus histones were measured. The minimum molecular weights were determined in concentrated solutions of guanidine hydrochloride. The results indicate that, with the possible exception of fraction F3, the fractions are heterogeneous. Comparisons in 0·1m-sodium chloride suggest that fraction F1 does not aggregate and show that fractions F2(a) and F3 aggregate to form larger complexes than does fraction F2(b). The degree of aggregation of each fraction is independent of pH in the range pH1–7. Detailed studies with fraction F2(b) have confirmed that the change in sedimentation coefficient observed as the sodium chloride concentration of the solution is increased results from increases in the apparent molecular weight of the sedimenting units. It has been found that the molecules of fraction F2(b) are present as single molecules only in sodium chloride solutions of 33mm or less. At these low concentrations the effects of charge greatly increase the concentration dependence of the sedimentation rate; the results can, however, be interpreted by using the theory developed by Alexandrowicz & Daniel (1963) and Daniel & Alexandrowicz (1963).

Masking of the Fc region in human IgG4 by constrained X-ray scattering modelling: implications for antibody function and therapy

2010 ◽  
Vol 432 (1) ◽  
pp. 101-114 ◽  
Author(s):  
Yuki Abe ◽  
Jayesh Gor ◽  
Daniel G. Bracewell ◽  
Stephen J. Perkins ◽  
Paul A. Dalby
Keyword(s):  
Concentration Dependence ◽  
Solution Structure ◽  
Analytical Ultracentrifugation ◽  
Sedimentation Coefficient ◽  
Radius Of Gyration ◽  
X Ray ◽  
X Ray Scattering ◽  
Starting Point ◽  
Self Association ◽  
Ray Scattering

Of the four human IgG antibody subclasses IgG1–IgG4, IgG4 is of interest in that it does not activate complement and exhibits atypical self-association, including the formation of bispecific antibodies. The solution structures of antibodies are critical to understand function and therapeutic applications. Thus IgG4 was studied by synchrotron X-ray scattering. The Guinier X-ray radius of gyration RG increased from 5.0 nm to 5.1 nm with an increase of concentration. The distance distribution function P(r) revealed a single peak at 0.3 mg/ml, which resolved into two peaks that shifted to smaller r values at 1.3 mg/ml, even though the maximum dimension of IgG4 was unchanged at 17 nm. This indicated a small concentration dependence of the IgG4 solution structure. By analytical ultracentrifugation, no concentration dependence in the sedimentation coefficient of 6.4 S was observed. Constrained scattering modelling resulted in solution structural determinations that showed that IgG4 has an asymmetric solution structure in which one Fab–Fc pair is closer together than the other pair, and the accessibility of one side of the Fc region is masked by the Fab regions. The averaged distances between the two Fab–Fc pairs change by 1–2 nm with the change in IgG4 concentration. The averaged conformation of the Fab regions appear able to hinder complement C1q binding to the Fc region and the self-association of IgG4 through the Fc region. The present results clarify IgG4 function and provide a starting point to investigate antibody stability.

scholarly journals Ribonucleic acid–deoxyribonucleic acid hybridization in aqueous solutions and in solutions containing formamide

1971 ◽  
Vol 125 (2) ◽  
pp. 481-487 ◽  
Author(s):  
S. Gillespie ◽  
D. Gillespie
Keyword(s):  
Sodium Chloride ◽  
Aqueous Solutions ◽  
Ribonucleic Acid ◽  
Deoxyribonucleic Acid ◽  
Sodium Citrate ◽  
Hybridization Reaction

Hybridization in 6×SSC (SSC, 0.15m-sodium chloride–0.015m-sodium citrate) at 66°C was compared with hybridization in formamide−6×SSC (1:1, v/v) at 35°C. As expected, the RNA hybridization potential was labile in the former system and stable in the latter. DNA retention by filters was poor in the formamide system, but could be improved. Several other properties of the hybridization reaction were explored and it was concluded that the formamide system is generally superior.

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