Light scattering and viscosity study of Poly-L-methionine

1970 ◽  
Vol 23 (9) ◽  
pp. 1801 ◽  
Author(s):  
JH Bradbury ◽  
BE Chapman
Keyword(s):  
Light Scattering ◽  
Organic Solvents ◽  
Trifluoroacetic Acid ◽  
Dichloroacetic Acid ◽  
Random Coil ◽  
Ethylene Dichloride ◽  
Viscosity Study ◽  
Polyelectrolyte Effect

Poly-L-methionine samples have been produced by polymerization of L- methionine-N-carboxyanhydride and their properties studied by light scattering and viscometry in organic solvents. In trifluoroacetic acid viscosity studies reveal a polyelectrolyte effect, hence the poly-L-methionine is charged. Furthermore, it is a random coil and fits the same Mark-Houwink equation as does poly-γ-benzyl-L-glutamate in dichloroacetic acid. Poly-L-methionine is a helical rod in ethylene dichloride + 2% dichloroacetic acid and shows the same viscometric behaviour as poly-y-benzyl-L-glutamate in dimethylformamide. Comparison of five different organic soluble polypeptides shows that there is an approximate correlation between the rigidity of the helix and its stability.

Nuclear magnetic resonance spectroscopy of denatured proteins

1969 ◽  
Vol 22 (5) ◽  
pp. 1083 ◽  
Author(s):  
JH Bradbury ◽  
NLR King
Keyword(s):  
Molecular Weight ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Trifluoroacetic Acid ◽  
Guanidine Hydrochloride ◽  
Dichloroacetic Acid ◽  
Random Coil ◽  
Resonance Spectroscopy ◽  
Line Broadening ◽  
Line Widths

The proton magnetic resonance spectroscopy of 11 proteins (molecular weight range 5700-650000) has been investigated in five denaturing solvents, viz., trifluoroacetic acid-d, formic acid, dichloroacetic acid, 6M guanidine hydrochloride in D2O, and 8M urea in D2O. The chemical shifts, line-widths, and intensities of the resonances have been measured of the histidine C2 protons, the methionine SCH3 protons and methyl protons of leucine, isoleucine, and valine, the aromatic protons, and the α-CH protons. ��� It is found that, with some exceptions delineated below, the line- widths of the methyl resonances are constant for a particular solvent, independent of the molecular weight of the protein. This indicates that, in general, the proteins behave as random coil structures in these solvents, which confirms the conclusion reached by Tanford and co-workers1-4 for 6M guanidine hydrochloride. ��� However, methyl line broadening occurs in dichloroacetic acid for catalase and fibrinogen, in guanidine hydrochloride for insulin, and in urea for insulin and lysozyme. Furthermore, the C 2 histidine resonance is absent in dichloroacetic acid solutions of thyroglobulin, catalase, and fibrinogen; the SCH3 resonance is absent in myoglobin in trifluoroacetic acid-d and occurs as a doublet for trypsin in guanidine hydrochloride and in urea. A general line broadening of resonances indicates association and/or incomplete unfolding of molecules, whereas perturbations of only one particular resonance, as in the cases detailed above, are probably due to intramolecular non-covalent interactions which involve the perturbed group and another unspecified group in the protein. ��

Random coil scission rates determined by time-dependent total intensity light scattering: Hyaluronate depolymerization by hyaluronidase

Biopolymers ◽  
1990 ◽  
Vol 30 (11-12) ◽  
pp. 1073-1082 ◽  
Author(s):  
Wayne F. Reed ◽  
Christopher E. Reed ◽  
Larry D. Byers
Keyword(s):  
Light Scattering ◽  
Time Dependent ◽  
Random Coil

scholarly journals Electrospinning and Post-Spun Chain Conformations of Synthetic, Hydrophobic Poly(α-amino acid)s

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 327 ◽  
Author(s):  
Kesavan Devarayan ◽  
Souta Nakagami ◽  
Shuichi Suzuki ◽  
Ichiro Yuki ◽  
Kousaku Ohkawa
Keyword(s):  
Amino Acid ◽  
Trifluoroacetic Acid ◽  
Average Molecular Weight ◽  
Helical Structure ◽  
Degree Of Polymerization ◽  
Random Coil ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Acid Anhydrides ◽  
Chain Conformations

Electrospinning and post-spun conformations of hydrophobic poly(α-amino acid)s are described in this study. The poly(α-amino acid)s, poly(Gly), poly(l-Ala), poly(l-Val), and poly(l-Leu) were synthesized via corresponding N-carboxy-α-amino acid anhydrides. The average molecular weight and degree of polymerization of these polymers were determined by N-terminus labeling using 2,4-dinitrofluorobenzene and by viscometry in the case of poly(Gly). These poly(α-amino acid)s were electrospun from trifluoroacetic acid or trifluoroacetic acid/dichloromethane solutions. The FT-IR spectroscopy and wide-angle X-ray diffraction indicated that the electrospun poly(l-Ala) and poly(l-Leu) fibers predominantly adopts α-helical structure, whereas poly(l-Val) and poly(Gly) fibers exhibited mainly β-strand and random coil structures, respectively.

Kinetics of the addition of acids to olefins with and without boron fluoride catalysis

1967 ◽  
Vol 45 (1) ◽  
pp. 11-16 ◽  
Author(s):  
G. A. Latrèmouille ◽  
A. M. Eastham
Keyword(s):  
Activation Energy ◽  
Acetic Acid ◽  
Apparent Activation Energy ◽  
Trifluoroacetic Acid ◽  
Similar Rate ◽  
Ethylene Dichloride ◽  
Kcal Mole ◽  
Rate Law ◽  
Boron Fluoride ◽  
Kinetics Of

Isobutene reacts readily with excess trifluoroacetic acid in ethylene dichloride solution at ordinary temperatures to give t-butyl trifluoroacetate. The rate of the reaction is given, within the range of the experiments, by the expression d[ester]/dt = k[acid]2[olefin], and the apparent activation energy is about 6 kcal/mole. The rate of addition is markedly dependent on the strength of the reacting acid and is drastically reduced in the presence of mildly basic materials, such as dioxane. The boron fluoride catalyzed addition of acetic acid to 2-butene can be considered to follow a similar rate law, i.e. d[ester]/dt = k[acid·BF3]2[olefin], but only if some assumptions are made about the position of the equilibrium [Formula: see text]since only the 1:1 complex is reactive.

Propriétés hydrodynamiques des conformations ordonnées et desordonnées du poly(γ-L-glutamate de benzyle): dimensions et flexibilité de la chaîne

1978 ◽  
Vol 56 (11) ◽  
pp. 1569-1574
Author(s):  
Nga Ho-Duc
Keyword(s):  
Quantitative Agreement ◽  
Dichloroacetic Acid ◽  
Random Coil ◽  
Hydrodynamic Properties ◽  
Molecular Weights ◽  
Coil Transition ◽  
Rigid Segment ◽  
Good Agreement ◽  
Stiff Chain

Theoretically we can determine the disordered or ordered structure of polypeptides and their dimensions in dilute solutions from hydrodynamic properties. We have presently a wealth of theories for random coil chains and a limited but sufficient number of theories for ordered chains for interpreting experimental results.Viscosity data for seven poly(γ-benzyl-L-glutamate) samples in 1,2-dichloroethane at 25 °C are analyzed and the length per monomeric residue (h) is calculated according to the equivalent ellipsoid approach. The degree of flexibility or rigidity is characterized by calculating Ns, the number of monomer units in a rigid segment or a Kuhn statistical segment; the determination of Ns is made by applying Yamakawa and Fujii's equation modified by Vitovskaya and Tsvetkov.Values obtained for h assuming the solute molecule to be a rigid, stiff chain, range between 1.3 to 2 Å. One notices that the h value close to 1.5 Å is found for the three following molecular weights: 1.8 × 105, 1.7 × 105, and 1.5 × 105. They are, in fact, the samples having a length in good quantitative agreement with that of the rigid segment determined by the method of Vitovskaya and Tsvetkov. This rigid segment corresponds to a sample of 700 ± 100 monomer units.The analysis of the experimental data of poly(γ-benzyl-L-glutamate) in dichloroacetic acid indicates that, in addition to the formation of hydrogen bonds, other interactions between the polypeptide and the solvent are present.In summary, we may conclude that the study of the helix–coil transition using hydrodynamic measurements is judged satisfactory but the determination of characteristic dimensions used to describe exactly the conformation of the macromolecule is somewhat ambiguous. One major problem is the degree of flexibility encountered with high molecular weight chains. However, to get around this difficulty, we propose, according to our results, a method which consists in determining the number of monomer units within a rigid segment from the different values found for h and then the dimensions from the samples for which the chain length is in good agreement with that of a rigid segment thus determined.

Photo-Crosslinking of Copolymeric Methacrylates Bearing Stilbene Chromophores

2012 ◽  
Vol 67 (11) ◽  
pp. 1132-1136
Author(s):  
Angelika Jahnke ◽  
Herbert Meier
Keyword(s):  
Light Scattering ◽  
Methyl Methacrylate ◽  
Radical Polymerization ◽  
Organic Solvents ◽  
Imaging Techniques ◽  
Ester Group ◽  
Cast Films ◽  
The Cross ◽  
Group Yield

Radical polymerization of methyl methacrylate (2) as major component and the methacrylates 1a or 1b, which contain an (E)-stilbene unit fixed by a tether to the ester group, yield easily soluble copolymers 3a, b. Whereas the dominant photoreactions in solution are (E)⇄Z) isomerizations and intra-chain [2π +2π] cycloadditions, cast films of 3a, b give an inter-chain photo-crosslinking on irradiation. Compared to homopolymers, the copolymers are not only better soluble and more easily processible, their films show less undesired light scattering. The cross-linked material is completely insoluble in organic solvents. Thus, it represents the basis for negative photoresists and the corresponding imaging techniques.

The Stability of Rotenone in a Phenol-oil Solution

1944 ◽  
Vol 35 (1) ◽  
pp. 1-2 ◽  
Author(s):  
G. G. Robinson
Keyword(s):  
Organic Solvents ◽  
Ethylene Dichloride ◽  
Yellow Colour ◽  
The Stability

It is known that, in solutions of some organic solvents such as pyridine, chloroform, ethylene dichloride and acetone, rotenone changes by oxidation to various derivatives, giving the solution a characteristic yellow colour (Jones & Haller, 1931). There is an accompanying loss in toxicity. Now that various intermediate solvents for rotenone in oils are being studied, it becomes of interest to know the stability of rotenone in these solutions.

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