Self-association of proteins. Self-association of α-chymotrypsin at its isoelectric point in buffer solutions of ionic strength 0.1

Biochemistry ◽  
1975 ◽  
Vol 14 (18) ◽  
pp. 4106-4110 ◽  
Author(s):  
M. W. Pandit ◽  
M. S. Narasinga Rao
Keyword(s):  
Ionic Strength ◽  
Isoelectric Point ◽  
Buffer Solutions ◽  
Self Association

Ethanol stability of casein micelles – a hypothesis concerning the role of calcium phosphate

1987 ◽  
Vol 54 (3) ◽  
pp. 389-395 ◽  
Author(s):  
David S. Horne
Keyword(s):  
Ionic Strength ◽  
Skim Milk ◽  
Buffer System ◽  
Casein Micelles ◽  
Buffer Solutions ◽  
Relative Response ◽  
Using Data ◽  
The Stability ◽  
Ethanol Stability

SummaryThe ethanol (EtOH) stability of skim milk and the stability towards aggregation of casein micelles diluted into ethanolic buffer solutions were compared using data obtained from previously published experiments. Differences in absolute stability and in relative response were observed when Ca2+ level and pH were adjusted, the buffer system results lying below those from skim milk in both cases. Increasing the ionic strength of skim milk adjusted to pH 7·0 lowered its EtOH stability whereas increasing the ionic strength of the diluting buffer increased the stability of the casein micelles. The hypothesis is put forward that the differences are due to the simultaneous precipitation of Ca phosphate when EtOH is added to skim milk. This draws calcium from the caseinate sites of the micelle, counteracting the destabilizing effects of the EtOH towards the micelle. Such removal and the consequent restructuring are kinetically controlled and micellar precipitation in skim milk finally occurs when the micellar coagulation time falls within the time scale of the restructuring reactions.

Solution pH That Minimizes Self-Association of Three Monoclonal Antibodies Is Strongly Dependent on Ionic Strength

2012 ◽  
Vol 9 (4) ◽  
pp. 744-751 ◽  
Author(s):  
Shantanu V. Sule ◽  
Jason K. Cheung ◽  
Valentyn Antochshuk ◽  
Amardeep S. Bhalla ◽  
Chakravarthy Narasimhan ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Ionic Strength ◽  
Solution Ph ◽  
Self Association

scholarly journals THE PROPERTIES OF MAMMALIAN STRIATED MYOFIBRILS ISOLATED BY AN ENZYMATIC METHOD

1950 ◽  
Vol 91 (6) ◽  
pp. 655-664 ◽  
Author(s):  
Armin F. Schick ◽  
George M. Hass
Keyword(s):  
Ionic Strength ◽  
Potassium Chloride ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Potassium Phosphate ◽  
Microscopic Structure ◽  
Buffer Solution ◽  
Buffer Solutions ◽  
Alkaline Side ◽  
Fresh Frozen

A new method for the isolation of large numbers of individual myofibrils from fresh mammalian skeletal and cardiac muscle has been described. Purification of isolated myofibrils was accomplished by differential centrifugation of fresh frozen sections of muscle which had been mechanically agitated after exposure for 30 to 45 minutes at 0°C. to the action of a dilute solution of trypsin in a phosphate buffer solution with a pH of 7.0 and an ionic strength of 0.25. Isolated skeletal myofibrils of the rabbit and man have similar constant solubility properties. They dissolve in an aqueous mixture of 0.5 N potassium chloride and 0.03 N sodium bicarbonate, giving viscous solutions which exhibit conspicuous birefringence of flow. They are soluble in buffer solutions (ionic strength 0.15) on the acid side of pH 4 and alkaline side of pH 10. If the ionic strength of potassium phosphate buffer solutions is increased to 0.5 or if the ionic strength of phosphate-borate buffer solutions is increased to a similar value by addition of potassium chloride, the isolated myofibrils become soluble at neutrality. Hence, it is possible, first to isolate the myofibrils and then dissolve them without deviating appreciably from physiologic ranges of pH. The extent to which myofibrils are modified by the conditions imposed by the method of isolation is unknown. There is no significant change in microscopic structure or optical birefringence. Furthermore, there is retention of a form of physiological reactivity, for when the isolated skeletal myofibrils are immersed in solutions of adenosinetriphosphate, they promptly and irreversibly change from elongated fibrils with distinct structural detail into dense spherical masses without recognizable microscopic structure.

scholarly journals Isolation and Self-Association Studies of Beta-Lactoglobulin

2020 ◽  
Vol 21 (24) ◽  
pp. 9711
Author(s):  
Adrian Gołębiowski ◽  
Paweł Pomastowski ◽  
Agnieszka Rodzik ◽  
Anna Król-Górniak ◽  
Tomasz Kowalkowski ◽  
...  
Keyword(s):  
Ammonium Sulfate ◽  
Isoelectric Point ◽  
Dispersion Medium ◽  
Sodium Citrate ◽  
Association Studies ◽  
Physicochemical Characterization ◽  
Protein Isolate ◽  
Flight Mass Spectrometry ◽  
Self Association ◽  
The Impact

The aim of this study was to investigate isolated β-lactoglobulin (β-LG) from the whey protein isolate (WPI) solution using the column chromatography with SP Sephadex. The physicochemical characterization (self-association, the pH stability in various salt solutions, the identification of oligomeric forms) of the protein obtained have been carried out. The electrophoretically pure β-LG fraction was obtained at pH 4.8. The fraction was characterized by the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/TOF MS) technique. The use of the HCCA matrix indicated the presence of oligomeric β-LG forms, while the SA and DHB matrices enabled the differentiation of A and B isoforms in the sample. The impact of sodium chloride, potassium chloride, ammonium sulfate, and sodium citrate in dispersion medium on β-LG electrophoretic stability in solution was also studied. Type of the dispersion medium led to the changes in the isoelectric point of protein. Sodium citrate stabilizes protein in comparison to ammonium sulfate. Additionally, the potential of capillary electrophoresis (CE) with UV detection using bare fused capillary to monitor β-LG oligomerization was discussed. Obtained CE data were further compared by the asymmetric flow field flow fractionation coupled with the multi-angle light scattering detector (AF4-MALS). It was shown that the β-LG is a monomer at pH 3.0, dimer at pH 7.0. At pH 5.0 (near the isoelectric point), oligomers with structures from dimeric to octameric are formed. However, the appearance of the oligomers equilibrium is dependent on the concentration of protein. The higher quantity of protein leads to the formation of the octamer. The far UV circular dichroism (CD) spectra carried out at pH 3.0, 5.0, and 7.0 confirmed that β-sheet conformation is dominant at pH 3.0, 5.0, while at pH 7.0, this conformation is approximately in the same quantity as α-helix and random structures.

scholarly journals Buffer solutions in drug formulation and processing: How pKa values depend on temperature, pressure and ionic strength

2019 ◽  
Vol 560 ◽  
pp. 357-364 ◽  
Author(s):  
Lisa Samuelsen ◽  
René Holm ◽  
Audrey Lathuile ◽  
Christian Schönbeck
Keyword(s):  
Ionic Strength ◽  
Drug Formulation ◽  
Pka Values ◽  
Buffer Solutions

scholarly journals Reversal of Flagellar Rotation Is Important in Initial Attachment of Escherichia coli to Glass in a Dynamic System with High- and Low-Ionic-Strength Buffers

2002 ◽  
Vol 68 (3) ◽  
pp. 1280-1289 ◽  
Author(s):  
Jennifer W. McClaine ◽  
Roseanne M. Ford
Keyword(s):  
Escherichia Coli ◽  
Ionic Strength ◽  
Cell Attachment ◽  
Fluid Velocity ◽  
Soft Particle ◽  
Wild Type ◽  
Buffer Solutions ◽  
Fluid Velocities ◽  
Significant Difference ◽  
Flagellar Rotation

ABSTRACT The attachment rates of wild-type, smooth-swimming, tumbly, and paralyzed Escherichia coli to glass was measured at fluid velocities of 0.0044 and 0.044 cms−1 (corresponding to shear rates of 0.34 and 3.4 s−1, respectively), in 0.02 and 0.2 M buffer solutions. At the highest ionic strength, we did not observe a significant difference in the attachment rate of wild-type and paralyzed cells at either fluid velocity. However, when the ionic strength was reduced, paralyzed bacteria attached at rates 4 and 10 times lower than that of the wild type under fluid velocities of 0.0044 and 0.044 cms−1, respectively. This suggested that the rotation of the flagella assisted in attachment. We then compared the attachment rates of smooth-swimming (counterclockwise rotation only) and tumbly (clockwise rotation only) cells to the wild type to determine whether the direction of rotation was important to cell attachment. At 0.0044 cms−1, the smooth-swimming cells attached at rates similar to that of the wild type in both buffer solutions but significantly less at the higher fluid velocity. Tumbly cells attached at much lower rates under all conditions. Thus, the combination of clockwise and counterclockwise flagellar rotation and their coupling appeared to be important in cell attachment. We considered a number of hypotheses to interpret these observations, including a residence time analysis and a comparison of traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to soft-particle theory.

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