scholarly journals Studies on Ovalbumin I. Denaturation By Heat, and the Heterogeneity of Ovalbumin

1964 ◽  
Vol 17 (1) ◽  
pp. 261 ◽  
Author(s):  
MB Smith
Keyword(s):  
Ionic Strength ◽  
Isoelectric Point ◽  
Protein Concentration ◽  
Optical Rotation ◽  
The State ◽  
Denatured Protein ◽  
Reduced Viscosity

The denaturation of ovalbumin by heat at pH 2-3 hus been studied by following the changes in optical rotation, viscosity, solubility at the isoelectric point, and amount of aggregated protein observed in the ultracentrifuge. The laevorotation and reduced viscosity of heated solutions of ovalbumin increa�se with ionic strength and protein concentration. This effect is related to the state of aggregation of the denatured protein and not to the extent of denaturation as measured by changes in solubility. The initial denaturation step is irreversible but does not involve the extensive unfolding observed in urea solutions.

scholarly journals THE IMMUNOCHEMISTRY OF TOXINS AND TOXOIDS

1948 ◽  
Vol 88 (2) ◽  
pp. 205-221 ◽  
Author(s):  
Louis Pillemer ◽  
Ruth G. Wittler ◽  
Jean I. Burrell ◽  
D. B. Grossberg
Keyword(s):  
Ionic Strength ◽  
Electrophoretic Mobility ◽  
Isoelectric Point ◽  
Molecular Species ◽  
Protein Concentration ◽  
Rabbit Serum ◽  
Clostridium Tetani ◽  
Sedimentation Constant ◽  
Veronal Buffer ◽  
Ultracentrifugal Analysis

Methods for the purification and crystallization of tetanal toxin are described. The methods consist of the multiphase fractionation system involving methanol as the organic precipitating agent under controlled conditions of pH, ionic strength, protein concentration, and temperature. Crystalline tetanal toxin has an electrophoretic mobility of 2.8 x 10–5 in veronal buffer of 0.1 ionic strength at pH 8.6. The solubility of freshly prepared toxin is essentially constant. The isoelectric point is 5.1 ± 0.1. The crystalline toxin contains 1 per cent sulfur, traces of phosphorus, and gives the usual protein reactions. It does not contain carbohydrate. The crystalline toxin does not precipitate anti-Clostridium tetani rabbit serum. The final product contains between 3400 and 3600 Lf and about 6.6 x 107 M.L.D. per mg. N. Crystalline tetanal toxin is spontaneously converted to a flocculating atoxic dimer upon standing at 0°. This change is accompanied by the appearance of another molecular species as judged by constant solubility tests. Ultracentrifugal analysis of these fractions reveals that tetanal toxin has a sedimentation constant of 4.5 Svedberg units while the atoxic flocculating dimer sediments at 7 S.

scholarly journals An Electrophoretic Study on "Component 2" Extracted From Wool With Alkaline Thioglycollate

1955 ◽  
Vol 8 (3) ◽  
pp. 378 ◽  
Author(s):  
JM Gillespie ◽  
FG Lennox
Keyword(s):  
Ionic Strength ◽  
Protein Concentration ◽  
Electrophoretic Pattern ◽  
Electrophoretic Study ◽  
Moving Peaks ◽  
Wool Keratin

Solutions of the thioglycollate-reduced wool keratin preparation, "component 2" of Gillespie and Lennox (1953, 1955), show abnormal electrophoretic behaviour. New, faster moving peaks appear in the descending electrophoretic pattern at protein concentrations exceeding 0�5 per cent. which are attributed to an aggregation-disaggregation reaction. They are eliminated by increasing the ionic strength to 0�5, or by lowering the protein concentration to 0�4 per cent.

scholarly journals Bridging interactions of proteins with silica nanoparticles: The influence of pH, ionic strength and protein concentration

Soft Matter ◽  
2014 ◽  
Vol 10 (5) ◽  
pp. 718-728 ◽  
Author(s):  
Bhuvnesh Bharti ◽  
Jens Meissner ◽  
Sabine H. L. Klapp ◽  
Gerhard H. Findenegg
Keyword(s):  
Ionic Strength ◽  
Silica Nanoparticles ◽  
Protein Concentration ◽  
Influence Of Ph

DETERMINATION OF THE CONSTANTS OF THE HENDERSON-HASSELBALCH EQUATION, (alpha)CO2 AND pKa, IN SEA TURTLE PLASMA

1993 ◽  
Vol 180 (1) ◽  
pp. 311-314 ◽  
Author(s):  
E. K. Stabenau ◽  
T. A. Heming
Keyword(s):  
Ionic Strength ◽  
Vapor Pressure ◽  
Blood Plasma ◽  
Water Content ◽  
Protein Concentration ◽  
Acid Base ◽  
Constant Weight ◽  
Blood Samples ◽  
Dissolved Species ◽  
Hasselbalch Equation

Hydration of CO2 yields HCO3- via the reaction: CO2 + H2O = H2CO3 = HCO3- + H+ = CO32- + 2H+. (1) Acid-base physiologists traditionally simplify the reaction by omitting the H2CO3 term and lumping all ionic CO2 species into the HCO3- term. The simplified reaction forms the basis for the familiar Henderson-Hasselbalch equation of the CO2-HCO3- buffer system: pH = pKa + log([HCO3-]/(alpha)CO2PCO2), (2) where (alpha)CO2 is the solubility coefficient relating [CO2] and PCO2 (Henry's Law). The apparent pK (pKa) in this equation lacks a rigorous thermodynamic definition. Instead, it is an empirical factor relating pH, the product of (alpha)CO2 and PCO2, and the apparent [HCO3-] (i.e. the sum of all ionic CO2 species). (alpha)CO2 and pKa are sensitive to the temperature, pH and/or the ionic strength of the reaction medium. (alpha)CO2 and pKa of normal mammalian blood plasma have been well defined over a range of temperatures and pH values (e.g. Severinghaus, 1965; Siggaard-Andersen, 1974; Reeves, 1976). These mammalian values are commonly used in analyses of the acid-base status of non- mammalian species, despite evidence that such practices can produce misleading results (Nicol et al. 1983). As an alternative, Heisler (1984; erratum in Heisler, 1986) developed complex equations for (alpha)CO2 (mmol l-1 mmHg-1) (1 mmHg=133.22 Pa) and pKa that are purported to be generally applicable to aqueous solutions (including body fluids) between 0 and 40 °C and incorporate the molarity of dissolved species (Md), solution pH, temperature (T, °C), sodium concentration ([Na+], mol l-1), ionic strength of nonprotein ions (I, mol l-1) and protein concentration ([Pr], g l-1): (alpha)CO2 = 0.1008 - 2.980 × 10–2Md + (1.218 × 10-3Md - 3.639 × 10-3)T - (1.957 × 10-5Md - 6.959 × 10-5)T2 + (7.171 × 10-8Md - 5.596 × 10-7)T3. (3) pKa = 6.583 - 1.341 × 10-2T + 2.282 × 10-4T2 - 1.516 × 10-6T3 - 0.341I0.323 - log{1 + 3.9 × 10-4[Pr] + 10A(1 + 10B)}, (4) where A = pH - 10.64 + 0.011T + 0.737I0.323 and B = 1.92 - 0.01T - 0.737I0.323 + log[Na+] + (0.651 - 0.494I)(1 + 0.0065[Pr]). Experimental validation of these equations has not appeared in the literature to date. We determined the (alpha)CO2 and pKa of blood plasma from Kemp's ridley sea turtles (Lepidochelys kempi Garman) and compared the values with those predicted from Heisler's equations. Blood samples were collected into heparinized syringes from the dorsal cervical sinus of 1- to 2-year- old animals at the National Marine Fisheries Service, Galveston Laboratory, Texas. Separated plasma was obtained by centrifugation of the whole blood samples. (alpha)CO2 was determined gasometrically by equilibrating 2 ml samples of acidified plasma (titrated to pH 2.5 with 1 mol l-1 HCl) in a tonometer with 99.9 % CO2 at 20, 25, 30 or 35 °C. Fresh samples of plasma were used at each temperature. The total CO2 content (CCO2) of plasma was measured in duplicate after 15 min of equilibration, using the methods described by Cameron (1971). The CO2 electrode (Radiometer, type E5036) was calibrated at each temperature using known [HCO3-]. Plasma PCO2 was calculated from the known fractional CO2 content of the equilibration gas, corrected for temperature, barometric pressure and water vapor pressure. Plasma water content was measured by weighing samples of plasma before and after they had been dried at 60 °C to constant weight. (alpha)CO2 was calculated as The quotient of CCO2 and PCO2, taking into account the plasma water content (mean +/− s.e.= 96+/−0.03 %). pKa was determined gasometrically by equilibrating 2 ml samples of plasma in a tonometer with 4.78 or 10.2 % CO2 (balance N2) at 20 or 30 °C. Fresh samples of plasma were used at each temperature and gas concentration. Plasma CCO2 and pH were measured in duplicate. The pH electrode (Radiometer, type G297/G2) was calibrated at each temperature using precision Radiometer pH buffers (S1500 and S1510). Plasma PCO2 was determined as above. pKa was calculated from a rearrangement of the Henderson-Hasselbalch equation (equation 2), assuming CCO2 to be the sum of [HCO3-] and [CO2] (i.e. (alpha)CO2PCO2). Heisler's equations were adapted for use with L. kempi plasma using measured values of the molarity of dissolved species (Md), [Na+] and protein concentration ([Pr]). These parameters were quantified as follows: Md with a vapor pressure osmometer (Precision Systems, model 5004), [Na+] by flame photometry (Jenway, model PFP7) and [Pr] by a standard spectrophotometric method (Sigma kit 541). The average values were Md=0.304+/−0.003 mol l-1, [Na+]=0.141+/−0.004 mol l-1 and [Pr]=28+/−3 g l- 1. The ionic strength of nonprotein ions (I) was assigned a value of 0.150 mol l-1. Computed (alpha)CO2 and pKa values were generated for a wider range of temperature and pH conditions than were used experimentally in order to emphasize the pattern and range of effects of temperature and/or pH.

scholarly journals Keratin Derivatives Extracted From Wool with Alkaline Thioglycollate Solutions

1955 ◽  
Vol 8 (1) ◽  
pp. 97 ◽  
Author(s):  
JM Gillespie ◽  
FG Lennox
Keyword(s):  
Ionic Strength ◽  
Protein Concentration ◽  
Anomalous Behaviour ◽  
Single Peak ◽  
Minor Components ◽  
Thioglycollic Acid ◽  
Merino Wool ◽  
Glycine Buffer ◽  
Initial Ph

In extension of previous work (Gillespie and Lennox 1953), the conditions under which proteins may be extracted from washed Merino wool have been further examined. Approximately 65 per cent. of the wool can be dissolved by a 40-min extraction at 50�C with O�1M thioglycollate at an initial pH of 12� 6. Electrophoresis at pH 11 in thioglycoIlate-glycine buffer indicated the presence of seven minor and one major component, the latter amounting to 41 per cent. of the wool. The minor components can be completely removed from the wool by five 2,O-min extractions with O�1M thioglycollate at an initial pH of 10�5. Extraction of the residue at pH 12�3 yields the major component. This moves as a single peak on electrophoresis between pH 8�0 and 12�0 in the presence of various buffers. It has a mobility of -7�2 X 10-5 cm2 V-I sec- I at a protein concentration of 0�5 per cent. in thioglycollate-glycine buffer of ionic strength O� 22 at pH 11� O. At higher protein concentrations there is anomalous behaviour on the descending boundary and tills can be prevented by increasing the ionic strength or replacing thioglycollic acid with mercapto-ethanol. The ascending pattern is unaltered by these changes or by increased protein concentration.

Gel properties of potato protein and the isolated fractions of patatins and protease inhibitors – Impact of drying method, protein concentration, pH and ionic strength

2019 ◽  
Vol 96 ◽  
pp. 246-258 ◽  
Author(s):  
Jesper Malling Schmidt ◽  
Henriette Damgaard ◽  
Mathias Greve-Poulsen ◽  
Anne Vuholm Sunds ◽  
Lotte Bach Larsen ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Protease Inhibitors ◽  
Protein Concentration ◽  
Drying Method ◽  
Gel Properties ◽  
Potato Protein

scholarly journals THE ISOELECTRIC POINTS OF THE PROTEINS IN CERTAIN VEGETABLE JUICES

1919 ◽  
Vol 2 (2) ◽  
pp. 145-160 ◽  
Author(s):  
Edwin J. Cohn ◽  
Joseph Gross ◽  
Omer C. Johnson
Keyword(s):  
Electric Field ◽  
Isoelectric Point ◽  
The State ◽  
Hydrogen Ion ◽  
Tomato Juice ◽  
Ion Concentration ◽  
Carrot Juice ◽  
Hydrogen Ion Concentration ◽  
Ion Concentrations ◽  
Isoelectric Points

The state in which a protein substance exists depends upon the nature of its combination with acids or bases and is changed by change in the protein compound. The nature of the compound of a protein that exists at any hydrogen ion concentration can be ascertained if the isoelectric point of the protein is known. Accordingly information regarding the isoelectric points of vegetable proteins is of importance for operations in which it may be desirable to change the state of protein substances, as in the dehydration of vegetables. The Protein in Potato Juice.—The hydrogen ion concentration of the filtered juice of the potato is in the neighborhood of 10–7N. Such juice contains the globulin tuberin to the extent of from 1 to 2 per cent. The character of the compound of tuberin that exists in nature was suggested by its anodic migration in an electric field. The addition of acid to potato juice dissociated this compound and liberated tuberin at its isoelectric point. The isoelectric point of tuberin coincided with a slightly lower hydrogen ion concentration than 10–4N. At that reaction it existed most nearly uncombined. The flow of current during cataphoresis was greatest in the neighborhood of the isoelectric point. This evidence supplements that of the direction of the migration of tuberin, since it also suggests the existence of the greatest number of uncombined ions near this point. At acidities greater than the isoelectric point tuberin combined with acid. The compound that was formed contained nearly three times as much acid as was needed to dissociate the tuberin compound that existed in nature. At such acidities tuberin migrated to the cathode. Though never completely precipitated tuberin was least soluble in the juice of the potato in the neighborhood of its isoelectric point. Both the compounds of tuberin with acids and with bases were more soluble in the juice than was uncombined tuberin. The nature of the slight precipitate that separated when potato juice was made slightly alkaline was not determined. The Protein in Carrot Juice.—The isoelectric point of the protein in carrot juice coincided with that of tuberin. Remarkably similar also were the properties of carrot juice and the juice of the potato. Existing in nature at nearly the same reaction they combined with acids and bases to nearly the same extent and showed minima in solubility at the same hydrogen ion concentrations. The greatest difference in behavior concerned the alkaline precipitate which, in the carrot, was nearly as great as the acid precipitate. The Protein in Tomato Juice.—The protein of the tomato existed in a precipitated form near its isoelectric point. Accordingly it was not present to any extent in filtered tomato juice. If, however, the considerable acidity at which the tomato exists was neutralized the protein dissolved and was filterable. It then migrated to the anode in an electric field. The addition of sufficient acid to make the hydrogen ion concentration slightly greater than 10–5N again precipitated the protein at its isoelectric point. At greater acidities migration was cathodic.

Studies on Characteristics and Adsorption of BSA on Hydrogel Biomaterials

2007 ◽  
Vol 330-332 ◽  
pp. 901-904
Author(s):  
G.X. Tan ◽  
Ying De Cui ◽  
Ying Jun Wang
Keyword(s):  
Ionic Strength ◽  
Bovine Serum Albumin ◽  
Chemical Stability ◽  
Contact Lens ◽  
Bovine Serum ◽  
Protein Concentration ◽  
Radical Copolymerization ◽  
Vinyl Pyrrolidone ◽  
Equilibrium Water Content ◽  
Influence Of Ph

Hydrogel biomaterials were synthesized by radical copolymerization of N-vinyl pyrrolidone (NVP) and 2-hydroxyethylmathacrylate (HEMA), with azobisisobutyronitrile (AIBN) as an initiator, reacting at 60~70°C for 24 hours, which were designed as contact lens due to the good chemical stability and high biocompatibility. The absorbency of bovine serum albumin (BSA) was measured by the ultraviolet spectrophotometer. The influence of pH, initial protein concentration and ionic strength were investigated in detail. The results showed that the absorption of protein on hydrogel biomaterials increased with the immersing time increasing, and was stable during 4 days. The absorption of protein on hydrogel increased with the equilibrium water content increasing. The protein absorption on hydrogels reduced the permeability of the oxygen of the biomaterials.

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