scholarly journals THE MOLECULAR WEIGHT AND ISOELECTRIC POINT OF THYROGLOBULIN

1935 ◽  
Vol 19 (1) ◽  
pp. 95-108 ◽  
Author(s):  
Michael Heidelberger ◽  
Kai O. Pedersen
Keyword(s):  
Molecular Weight ◽  
Isoelectric Point ◽  
Specific Volume ◽  
Sedimentation Equilibrium ◽  
Sedimentation Constant ◽  
Diffusion Constants ◽  
Equilibrium Data ◽  
Round Numbers ◽  
And Diffusion

1. The sedimentation constant of hog thyroglobulin is 19.2ċ10–13. That of human thyroglobulin is essentially the same. 2. The specific volume of hog thyroglobulin is 0.72. 3. The isoelectric point of native hog thyroglobulin is at pH 4.58, that of denatured thyroglobulin at pH 5.0. 4. The molecular weight of hog thyroglobulin is, in round numbers, 700,000, as calculated from the sedimentation and diffusion constants, or 650,000, as calculated from the sedimentation equilibrium data. 5. The thyroglobulin molecule deviates markedly from the spherical.

scholarly journals THE PROTEINS IN UNHEATED CULTURE FILTRATES OF HUMAN TUBERCLE BACILLI

1948 ◽  
Vol 87 (3) ◽  
pp. 229-244 ◽  
Author(s):  
Ellen B. Bevilacqua ◽  
Janet R. McCarter
Keyword(s):  
Molecular Weight ◽  
Diffusion Rate ◽  
Sedimentation Velocity ◽  
Partial Specific Volume ◽  
Velocity Measurements ◽  
Physical Measurements ◽  
Sedimentation Constant ◽  
Diffusion Constants ◽  
Culture Filtrates ◽  
And Diffusion

Concentrated culture filtrates of two strains of human tubercle bacilli, a virulent and a slightly virulent one, have been fractionated to give fourteen fractions in each case. Chemical determinations and sedimentation velocity measurements have been carried out on those fractions for which significant results could be obtained. The evidence is that two distinct proteins are present, in addition to a polysaccharide and nucleic acid. The physical measurements have not demonstrated the presence of any other proteins. One of the proteins has been isolated in pure form, and found to have a molecular weight of 44,000 ± 5,000, based on measurements of partial specific volume, sedimentation velocity, and diffusion rate. This protein is believed to be the same as one previously isolated by Seibert et al. (6), who assigned it a molecular weight of 32,000. The other protein was not obtained sufficiently free from polysaccharide so that its molecular weight could be determined, but it is believed to have a sedimentation constant of about 2 S. Sedimentation and diffusion constants have been obtained for the polysaccharide, which appears to be a homogeneous molecular species with a molecular weight of about 20,000. The source in unheated tuberculin of the proteins obtained from heated preparations is discussed.

scholarly journals THE LS-ANTIGEN OF VACCINIA

1943 ◽  
Vol 77 (2) ◽  
pp. 155-164 ◽  
Author(s):  
Theodore Shedlovsky ◽  
Alexandre Rothen ◽  
Joseph E. Smadel
Keyword(s):  
Molecular Weight ◽  
Isoelectric Point ◽  
Specific Volume ◽  
Degradation Products ◽  
Diffusion Constant ◽  
Partial Specific Volume ◽  
Analytical Ultracentrifuge ◽  
Axis Ratio ◽  
Ellipsoidal Shape ◽  
Sedimentation Constant

Studies on LS-protein, the soluble double antigen of vaccinia, and on the degradation products L'S and L''S' have been made with electrophoresis and in the analytical ultracentrifuge. LS, which is homogeneous electrically and in the ultracentrifuge, has an isoelectric point at pH 4.8. At 4°C. its partial specific volume is 0.72 cc./gm., and its diffusion constant is 1.50 x 10–7 cm.2/sec. The sedimentation constant is 6.35 at 20°C., the molecular weight is 214,000, and the molecule appears to have an elongated ellipsoidal shape with an axis ratio of 1:20. L'S and L''S' are homogeneous electrically but not in the ultracentrifuge, L''S' being extremely polydisperse.

ULTRACENTRIFUGE AND DIFFUSION STUDIES ON GLUTEN

1942 ◽  
Vol 20c (3) ◽  
pp. 130-159 ◽  
Author(s):  
A. G. McCalla ◽  
Nils Gralén
Keyword(s):  
Sodium Salicylate ◽  
Minimum Weight ◽  
Average Molecular Weight ◽  
Sedimentation Equilibrium ◽  
Velocity Sedimentation ◽  
Molecular Characteristics ◽  
Weight Average Molecular Weight ◽  
Diffusion Constants ◽  
Diffusion Studies ◽  
And Diffusion

The molecular characteristics of gluten in sodium salicylate solutions were studied by means of sedimentation velocity, sedimentation equilibrium, and diffusion measurements. The proportion of total gluten protein molecularly dispersed increased with increase in concentration of sodium salicylate up to 12%, but the dispersed portions had essentially the same sedimentation constant (2.5 ± 0.15) regardless of the concentration of the dispersing medium.The most soluble 25 per cent of the gluten was all molecularly dispersed, but was definitely inhomogeneous. The weight-average molecular weight of this fraction was 44,000, but there is reason to believe the minimum weight may be about 35,000. None of the other fractions was entirely molecularly dispersed, the proportion decreasing with decreasing solubility of the fractions. Aggregates of many sizes existed in all of these fractions, but only the most insoluble contained aggregates large enough to cause opacity. Sedimentation constants of the molecularly dispersed portions increased slightly with decreasing solubility, while diffusion constants decreased markedly. None of the fractions yielded normal curves (diffusion diagrams) but the more soluble the fraction, the more nearly normal the curve. The inhomogeneity responsible for the varying rates of diffusion was due partly to differences in proportion and properties of the molecularly dispersed gluten and partly to aggregates.All properties showed progressive changes both within and between the arbitrarily produced fractions. These results, therefore, support the hypothesis that gluten is a protein system showing progressive and regular changes in properties with change in solubility.

scholarly journals MOLECULAR WEIGHT AND ELECTROPHORESIS OF CRYSTALLINE RIBONUCLEASE

1940 ◽  
Vol 24 (2) ◽  
pp. 203-211 ◽  
Author(s):  
Alexandre Rothen
Keyword(s):  
Molecular Weight ◽  
Isoelectric Point ◽  
Unit Weight ◽  
Diffusion Measurement ◽  
Average Value ◽  
Rate Of Sedimentation ◽  
And Diffusion ◽  
Good Agreement

Electrophoretic studies on purified crystalline ribonuclease showed the absence of any impurities differing in mobility from the bulk of material. The isoelectric point of ribonuclease was found by electrophoresis to be at about pH 7.8. Ultracentrifuge studies indicated fair homogeneity of ribonuclease in solution. Only one moving component has been observed. The molecular weight of ribonuclease was found to be 12,700 from rate of sedimentation (S25 = 1.85 x 10–13 in 0.5 M (NH4)2SO4) and diffusion measurement (D = 1.36 x 10–6 in 0.5 M (NH4)2SO4), in good agreement with the average value of 13,000 found from equilibrium measurements. This low value for the molecular weight of a protein would seem to discredit the value 17,600 as representing a universal unit weight for proteins in general.

scholarly journals PURIFIED DIPHTHERIA ANTITOXIN IN THE ULTRACENTRIFUGE AND IN THE ELECTROPHORESIS APPARATUS

1942 ◽  
Vol 25 (3) ◽  
pp. 487-496 ◽  
Author(s):  
Alexandre Rothen
Keyword(s):  
Molecular Weight ◽  
High Activity ◽  
Isoelectric Point ◽  
Diffusion Constant ◽  
Enzymatic Treatment ◽  
Trypsin Digestion ◽  
Globulin Fraction ◽  
Sedimentation Constant ◽  
Diphtheria Antitoxin ◽  
Horse Plasma

Ultracentrifugation studies of diphtheria antitoxin showed that: 1. Purified antitoxin of high activity obtained from horse plasma without enzymatic treatment has exactly the same sedimentation constant as the globulin fraction obtained in a similar way from normal horse plasma s20water = 6.9 x 10–13. 2. Purified antitoxin obtained with trypsin digestion of the toxin-antitoxin complex has a sedimentation constant of s20water = 5.5 ± 0.1 x 10–13, a diffusion constant of D20water = 5.76 x 10–7, and a molecular weight of about 90,000. Electrophoresis experiments demonstrated that: 1. The trypsin-purified antitoxin has an isoelectric point not far from pH 7.0. 2. The reversible spreading noticed at about pH 7.3 cannot be attributed to heterogeneous preparation. 3. The large increase in the γ-globulin fraction occurring during immunization consists either of antitoxin of various degrees of activity or of some inert protein in addition to the antitoxin.

scholarly journals Purification and properties of malyl-coenzyme A lyase from Pseudomonas AM1

1974 ◽  
Vol 139 (2) ◽  
pp. 399-405 ◽  
Author(s):  
A. J. Hacking ◽  
J. R. Quayle
Keyword(s):  
Molecular Weight ◽  
Thiol Group ◽  
Sedimentation Equilibrium ◽  
Cleavage Reaction ◽  
Acetyl Coa ◽  
Bivalent Cation ◽  
Optimal Activity ◽  
Purification And Properties ◽  
Equilibrium Data ◽  
Michaelis Constants

1. Malyl-CoA lyase was purified 20-fold from extracts of methanol-grown Pseudomonas AM1. 2. Preparations of the enzyme were essentially homogeneous by electrophoretic and ultracentrifugal criteria. 3. Malyl-CoA lyase has a molecular weight of 190000 determined from sedimentation-equilibrium data. 4. Within the range of compounds tested, malyl-CoA lyase is specific for (2S)-4-malyl-CoA or glyoxylate and acetyl-CoA or propionyl-CoA. 5. A bivalent cation is essential for activity, Mg2+ or Co2+ being most effective. 6. Malyl-CoA lyase is inhibited by (2R)-4-malyl-CoA and by some buffers, but thiol-group inhibitors are without effect. 7. Optimal activity was recorded at pH7.8. 8. An equilibrium constant of 4.7×10−4m was determined for the malyl-CoA cleavage reaction. 9. The Michaelis constants for the enzyme are: 4-malyl-CoA, 6.6×10−5m; acetyl-CoA, 1.5×10−5m; glyoxylate, 1.7×10−3m; Mg2+, 1.2×10−3m.

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