PHYSICOCHEMICAL STUDIES OF ALKALI LIGNINS: III. SIZE AND SHAPE OF THE MACROMOLECULE

1960 ◽  
Vol 38 (2) ◽  
pp. 270-279 ◽  
Author(s):  
P. R. Gupta ◽  
D. A. I. Goring
Keyword(s):  
Molecular Weight ◽  
Sedimentation Coefficient ◽  
Random Coil ◽  
Alkali Lignin ◽  
Molecular Weights ◽  
A Value ◽  
Huggins Constant ◽  
Physicochemical Studies ◽  
Lignin Macromolecule ◽  
Very High

Light-scattering measurements were made on the alkali lignin fractions described in a previous paper. The range of molecular weights found was from 50,000 to 48 × 106. The usual logarithmic graph of intrinsic viscosity and molecular weight was linear and gave a value of 0.32 for the exponent. From the logarithmic sedimentation coefficient – molecular weight relationship, the exponent was found as 0.52. Flory's hydrodynamic parameter [Formula: see text] was 2.3 × 106. These results suggested that the configuration of the alkali lignin macromolecule conformed to a structure between that of a random coil and an Einstein's sphere impenetrable to solvent. The branching parameter, g, introduced by Zimm and Stockmayer, decreased with an increase in molecular weight as expected. Most of the values of Huggins' constant, k′,were between 1 and 2 which indicated a compact particle. A marked increase in k′ was noted for fractions of low or very high molecular weight. The significance of the data is discussed and a model tentatively suggested for the macromolecule.

Physicochemical and chemical studies on wheat embryo ribosomal proteins

1968 ◽  
Vol 46 (4) ◽  
pp. 373-380 ◽  
Author(s):  
Fred H. Wolfe ◽  
Cyril M. Kay
Keyword(s):  
Molecular Weight ◽  
Ribosomal Proteins ◽  
High Speed ◽  
Polyacrylamide Gel Electrophoresis ◽  
Average Molecular Weight ◽  
Optical Rotatory Dispersion ◽  
Random Coil ◽  
Wheat Embryo ◽  
Molecular Weights ◽  
A Value

The physical heterogeneity of unfractionated wheat embryo ribsomal proteins, prepared by the glacial acetic acid method of Waller and Harris, has been investigated in 8 M urea −10−3 M dithio-threitol solutions of low pH (4.5). Sedimentation–diffusion measurements resulted in a weight average molecular weight of 29 000 ± 2 500, with no obvious evidence of heterogeneity. High-speed membrane osmometry was employed to establish the number average molecular weight of this system as 24 500 ± 1 000. The disparity in molecular weight averages suggests some size heterogeneity, and statistical analysis based on the two average molecular weights resulted in a calculated range of molecular weights for wheat embryo ribosomal proteins from 15 000 to 34 000 a.m.u. Charge differences, reflecting presumably primary structure differences, also exist among the members of this class, since about 26 different bands were resolved on polyacrylamide gel electrophoresis. The weight intrinsic viscosity of the ribosomal proteins in 8 M urea solutions was established as 0.273 dl/g, a value considerably larger than most globular proteins, suggesting that a major portion of their polypeptide chains are unfolded in this solvent. This conclusion was substantiated by optical rotatory dispersion measurements on this system, which resulted in a dispersion constant, λc, of 213 m μ, a value typical of that of the random coil. Amino acid and N-terminal analyses are also reported for this system, and comparisons of both chemical and physicochemical parameters are made with ribosomal proteins of other sources.

scholarly journals Inducible overexpression and secretion of int-1 protein.

1989 ◽  
Vol 9 (8) ◽  
pp. 3377-3384 ◽  
Author(s):  
J Papkoff
Keyword(s):  
Molecular Weight ◽  
Cho Cells ◽  
Secretory Pathway ◽  
Mammary Tissue ◽  
Neural Tubes ◽  
Molecular Weights ◽  
Activation Of Transcription ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Very High

The int-1 proto-oncogene is a target for insertional activation of transcription by mouse mammary tumor virus in many murine mammary tumors. Whereas no expression of int-1 is seen in normal mammary tissue, int-1 RNA can be detected in normal mice in the neural tubes of midgestation embryos and in postmeiotic spermatocytes from adult testes. I report here the results of a study in which several different antibodies against synthetic peptides were produced and used to characterize the processing and secretion of int-1 protein. CHO cells were transfected with an inducible int-1 expression vector that was subsequently amplified to generate cell lines expressing very high levels of int-1 protein. Immunoprecipitation of [35S]cysteine-labeled cell lysates from these CHO cells yielded large amounts of four immature forms of int-1 glycoprotein (molecular weights of 36,000, 38,000, 40,000, and 42,000). A significant fraction of these int-1 species formed disulfide-linked multimers. Pulse-chase and glycosidase digestion studies demonstrated that some of the immature species of int-1 protein move through the secretory pathway and are processed to a mature heterogeneous glycoprotein with a molecular weight of about 44,000. Suramin treatment of the CHO cells during pulse-chase experiments increased the amount of 44,000-molecular-weight int-1 protein in the culture medium.

Measurement of the Isothermal Volume Dilation Accompanying the Unilateral Extension of Rubber

1959 ◽  
Vol 32 (2) ◽  
pp. 428-433
Author(s):  
Fred G. Hewitt ◽  
Robert L. Anthony
Keyword(s):  
Molecular Weight ◽  
Young’S Modulus ◽  
Experimental Results ◽  
Molecular Weights ◽  
Rubber Specimen ◽  
A Value ◽  
Fractional Increase ◽  
Internal Agreement ◽  
Good Agreement

Abstract The fractional increase in volume accompanying the isothermal extension of soft gum rubber was measured for four rubber samples at mean extensions of 14, 33, and 51%. The chain molecular weights Mc of the four samples were 5500, 5100, 4400, and 3000, with an estimated uncertainty of about 10% in each value of Mc. The observed fractional increase in volume ranged from 3.2×10−5 to 142×10−5, the latter value being observed for the sample of lowest chain molecular weight and at the extension of 51%. The experimental results for each sample have been represented by theoretical curves based on Gee's expression for the fractional increase in volume as a function of the sample extension. The theoretical curves exhibit good agreement with those of Gee, Stern, and Treloar. The process of fitting the theoretical curves to the experimental points constituted a determination of Young's modulus E for each rubber specimen. As a check on the experimental results, and also on the theory employed, determinations of E were also made by two additional methods, namely, from rough stess-strain curves, and from the relation E=3γρRT/Mc. With one exception, the internal agreement between the three determinations of E for the four different samples was satisfactory. The exception noted can probably be ascribed to the use of too small a value of Mc for the sample of lowest chain molecular weight.

Molecular Weight Effects in Adsorption of Rubbers on Carbon Black

1968 ◽  
Vol 41 (5) ◽  
pp. 1256-1270 ◽  
Author(s):  
Gerard Kraus ◽  
J. T. Gruver
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Large Particle ◽  
Molecular Weights ◽  
Molecular Weight Dependence ◽  
Bound Rubber ◽  
Sieve Effect ◽  
High Structure ◽  
Very High ◽  
Poor Solvent

Abstract The molecular weight dependence of the adsorption of polybutadiene on carbon black from a poor solvent, n-heptane, and bulk, i.e., the phenomenon of “bound rubber”, was investigated. For narrow distribution polymers the adsorption is proportional to Mn, where n = 0.14 for adsorption from n-heptane solution; n = 0.5 for adsorption from bulk. Anomalously low solution adsorption was observed for polymers of very high molecular weight (> 500,000). This is ascribed to a sieve effect by aggregates of carbon black particles which cannot be penetrated by the large molecular coils. In high structure blacks, which pack more loosely, and in large particle blacks, which form larger interstices between particles, onset of anomalous adsorption is shifted toward higher molecular weights.

scholarly journals The Isolation and Properties of Some Soluble Proteins From Wool VI. The Physicochemical Properties of Sgmkb2

1963 ◽  
Vol 16 (1) ◽  
pp. 252 ◽  
Author(s):  
JM Gillespie ◽  
BS Harrap
Keyword(s):  
Molecular Weight ◽  
No Reduction ◽  
Sedimentation Coefficient ◽  
Chain Structure ◽  
Optical Rotatory Dispersion ◽  
Random Coil ◽  
Merino Wool ◽  
Frictional Properties ◽  
Dispersion Data ◽  
End Group

The molecular weight of a high-sulphur protein (SCMKB2) from Merino wool has been determined by the Archibald technique and by light scattering, values of 22,600 and 22,100, respectively, being obtained. Optical rotatory dispersion data show that in aqueous solution the protein behaves as a random coil. This is consistent with the frictional properties of the molecule as deduced from its sedimentation coefficient and intrinsic viscosity. The protein appears to have one N-terminal arginyl end group; since it also contains two acyl groups per 22,000 molecular weight unit, the possibility of a multi�chain structure for the protein unit has been considered. However, no reduction in molecular weight could be achieved in any of several disaggregating solvents.

scholarly journals Molecular weights of the Thy-1 glycoproteins from rat thymus and brain in the presence and absence of deoxycholate

1978 ◽  
Vol 169 (2) ◽  
pp. 411-417 ◽  
Author(s):  
P W Kuchel ◽  
D G Campbell ◽  
A N Barclay ◽  
A F Williams
Keyword(s):  
Molecular Weight ◽  
Equilibrium Dialysis ◽  
Sedimentation Coefficient ◽  
Sedimentation Equilibrium ◽  
Membrane Glycoproteins ◽  
Guanidinium Chloride ◽  
Molecular Weights ◽  
Methionine Residue ◽  
Disulphide Bonds ◽  
Binding Data

1. The Thy-1 membrane glycoproteins from rat thymus and brain bound deoxycholate to 24% of their own weight as measured by equilibrium dialysis. The binding occurred co-operatively at the critical micelle concentration of deoxycholate, suggesting that the glycoproteins bind to a micelle, and not to the detergent monomer. 2. From sedimentation-equilibrium and deoxycholate-binding data the molecular weights of the glycoprotein monomers were calculated to be 18700 and 17500 for thymus and brain Thy-1 glycoprotein monomers were calculated to be 18700 and 17500 for thymus and brain Thy-1 glycoproteins respectively. The molecular weight of the polypeptide part of the glycoprotein is thus 12500. 3. In the absence of deoxycholate, brain or thymus Thy-1 glycoprotein formed large homogeneous complexes of mol. wt. 270000 or 300000 respectively. The sedimentation coefficient of these was 12.8 S. The complex was only partially dissociated by 4M-guanidinium chloride. 4. After cleavage of brain or thymus Thy-1 glycoprotein with CNBr, two peptides were clearly identified. They were linked by disulphide bonds and both contained carbohydrate. This cleavage suggests there is only one methionine residue per molecule, which is consistent with the above molecular weights and the known amino acid composition.

Stability of acetylcholinesterase in guanidine hydrochloride solution

1981 ◽  
Vol 59 (7) ◽  
pp. 551-555 ◽  
Author(s):  
Faizan Ahmad
Keyword(s):  
Molecular Weight ◽  
Guanidine Hydrochloride ◽  
Sedimentation Coefficient ◽  
Conformational State ◽  
Random Coil ◽  
Aromatic Residues ◽  
Activity Measurements ◽  
Irreversible Unfolding ◽  
Hydrochloride Solution ◽  
Circular Dichroic

The irreversible unfolding of acetylcholinesterase (acetylcholine hydrolyase, EC 3.1.1.7) by guanidine hydrochloride was studied by difference spectral, circular dichroic, and enzyme activity measurements. At pH 7.0 and in 1.1 M denaturant solution, a conformational state in which enzyme is completely inactive was detected. It is identical to the native enzyme as far as sedimentation coefficient and molecular weight are concerned, but differs from the native molecule by a slight loss in secondary structure and by a small perturbation of aromatic residues. Acetylcholinesterase in concentrated guanidine hydrochloride solution containing β-mercaptoethanol dissociates and exists as a random coil of molecular weight 68 000.

scholarly journals The molecular weights of two forms of carbamoyl phosphate synthase from rat liver

1972 ◽  
Vol 127 (3) ◽  
pp. 503-508 ◽  
Author(s):  
R. Virden
Keyword(s):  
Molecular Weight ◽  
Concentration Dependence ◽  
Rat Liver ◽  
Chemical Equilibrium ◽  
High Speed ◽  
Carbamoyl Phosphate ◽  
Molecular Weights ◽  
A Value ◽  
Equilibrium Sedimentation ◽  
Phosphate Synthase

1. N-Acetylglutamate-dependent carbamoyl phosphate synthase from rat liver was centrifuged in sucrose density gradients. The concentration-dependence of s was consistent with a chemical equilibrium existing between the 11S and 7.5S forms of the enzyme. 2. Under conditions favouring the 11S form, the properties of the enzyme in ultra-short-column equilibrium experiments suggest a molecular weight of 316000±42000 for the 11S form. 3. Under conditions favouring the 7.5S form, high-speed equilibrium-sedimentation measurements gave a value of 160000±10000 as the molecular weight of the 7.5S form of the enzyme.

Molecular Weight of Legumin From Pisum sativum

1980 ◽  
Vol 7 (3) ◽  
pp. 221 ◽  
Author(s):  
RJ Blagrove ◽  
GG Lilley ◽  
R Davey
Keyword(s):  
Molecular Weight ◽  
Recent Literature ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sedimentation Equilibrium ◽  
Pumpkin Seed ◽  
Subunit Molecular Weight ◽  
A Value ◽  
Oligomeric Protein ◽  
Physicochemical Studies ◽  
Pea Seed

There have been many physicochemical studies of legumin, one of the major storage globulins isolated from pea seed. The more recent literature values for the molecular weight of this protein are in the range 390 000-420 000. These results are not consistent with the subunit molecular weight of legumin determined by dodecyl sulfate-polyacrylamide gel electrophoresis, if a hexameric model is assumed. We have measured the molecular weight of a highly purified sample of Pisum legumin by meniscus depletion sedimentation equilibrium and have found a value of 350 000 � 10 000. Since the oligomeric protein is homogeneous with respect to molecular weight, the heterogeneity reported for the subunit polypeptides, using various conditions of electrophoresis, presumably reflect differences in charge and amino acid composition. The molecular weight of legumin is significantly greater than the value of 325 000 found for cucurbitin, the equivalent crystalline protein isolated from pumpkin seed.

FATTY ACIDS AND THEIR ESTERS: II. MOLECULAR WEIGHTS OF POLYMERIZED ESTERS

1936 ◽  
Vol 14b (6) ◽  
pp. 231-236
Author(s):  
H. N. Brocklesby
Keyword(s):  
Fatty Acids ◽  
Molecular Weight ◽  
Unsaturated Fatty Acids ◽  
Normal Values ◽  
Linseed Oil ◽  
Molecular Weights ◽  
A Value

When a value of K that allows for the effect of the solute on the dissociation of the solvent is used, raw linseed oil shows normal values for the molecular weight when determined cryoscopically or ebullioscopically in a number of diverse solvents. Similarly, polymerized oils and esters show identical molecular weights in different solvents when determined either cryoscopically or ebullioscopically. The data indicate that polymerized esters of unsaturated fatty acids cannot be assumed to be associated.

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