scholarly journals Assessment of Conformational Changes in Low-Sulphur S-Carboxymethylkerateine from Wool

1967 ◽  
Vol 20 (4) ◽  
pp. 827 ◽  
Author(s):  
GM Bhatnagar ◽  
WG Crewther
Keyword(s):  
Absorption Spectrum ◽  
Conformational Changes ◽  
Guanidine Hydrochloride ◽  
Ultraviolet Absorption Spectrum ◽  
Spectral Measurements ◽  
Characteristic Difference ◽  
Concentrated Solutions ◽  
Difference Spectra ◽  
The Difference ◽  
Negative Difference

The effects of urea and guanidine hydrochloride on the ultraviolet absorption spectrum of the low-sulphur S-carboxymethylkerateine fraction of wool have been measured. In concentrated solutions of urea characteristic difference spectra were obtained with maxima of negative absorbance at 288, 280, and 240 miL. The addition of guanidine hydrochloride or an increase in temperature gave similar negative difference maxima at the higher wavelengths. Calculation of the extent of unfolding of the protein chains from the difference in absorbance at all three maxima showed that the unfolding was 50% complete at a urea concentration of about 1� 8M whereas a urea concep.tration of about 4� 3M was required to decrease the helix content by 50%. Similar measurements on components 7 and 8, the two major constituents of SCMKA, showed that a 50% decrease in helix content was obtained with 2�8M and O� 8M urea respectively whereas the corresponding values for 50 % unfolding assessed from difference spectral measurements were 2� 2M and 1� 2M urea respectively. It is suggested that the helical regions of components 7 and 8 aggregate specifically and that spectral measurements relate largely to non-helical portions of the chains.

Occurrence of c-Type Cytochrome in Mycobacterium lepraemurium

1974 ◽  
Vol 52 (11) ◽  
pp. 991-996 ◽  
Author(s):  
M. Ishaque ◽  
L. Kato
Keyword(s):  
Absorption Spectrum ◽  
Cytochrome C ◽  
Cytochrome B ◽  
Antimycin A ◽  
Alpha Band ◽  
Difference Spectra ◽  
Absorption Bands ◽  
Type C ◽  
The Difference ◽  
Mycobacterium Lepraemurium

The existence of c-type cytochrome in Mycobacterium lepraemurium was examined. The dithionite-treated cell-free extracts exhibited absorption peaks of cytochromes a + a3 and b, whereas the alpha band of c-type cytochrome at 552 nm was obscured by the large absorption peak of cytochrome b at 560 nm. The addition of NADH, NADPH, or succinate to cell-free extracts caused the reduction of b- and c-type cytochromes to nearly the same extent and thus the difference spectra displayed distinct separate peaks of b- and c-type cytochromes at 562 and 552 nm, respectively. The cell-free extracts treated with ascorbate showed absorption bands of cytochrome types c and a + a3, whereas the addition of succinate to a system preinhibited by antimycin A revealed the absorption bands of cytochrome b only. The absorption spectrum of the pyridine hemochromogens of M. lepraemurium was similar to that of mammalian cytochrome c. The results clearly indicated that, in addition to cytochromes of the a + a3 and b type, c-type cytochrome is also present in M. lepraemurium.

The self-association of glycosyl phenylazo dyes (Yariv antigens)

1978 ◽  
Vol 31 (10) ◽  
pp. 2225 ◽  
Author(s):  
EF Woods ◽  
GG Lilley ◽  
MA Jermyn
Keyword(s):  
Guanidine Hydrochloride ◽  
Sodium Dodecyl ◽  
Entropy Change ◽  
Wide Distribution ◽  
Enthalpy Change ◽  
Spectral Measurements ◽  
Concentrated Solutions ◽  
Weight Concentration ◽  
Equilibrium Sedimentation ◽  
Self Association

The aggregation of tris(4-glycosyloxyphenylazo)phloroglucinol compounds (Yariv antigens) where glyco = β-D-gluco, β-D-manno, β-D-galacto and α- D-galacto has been investigated by equilibrium sedimentation, the photoelectric scanning absorption optical system being utilized. The compounds have been shown to undergo a strong self-association in water and an analysis procedure employing Laplace transforms indicated a very wide distribution of species in the ultracentrifuge cell at equilibrium. To determine the type of association the concentration of monomer as a function of total weight concentration was calculated by using the recently developed Ω function. When the concentration of monomer is very low, as in the present case, the analysis is difficult because very slight curvature in the Ω-function plot has a large effect on the extrapolation to zero concentration. ��� The results are best described by an isodesmic indefinite self- association. The β-glucoside Yariv antigen was the most extensively investigated and the most highly purified sample was shown to have an association constant of 2.5 x 107 l. mol-1. The order of the association constants of the Yariv compounds was found to be β-glucoside > β- galactoside > α-galactoside > β-mannoside. For the β-glucoside compound an increase in temperature favours species of lower molecular weight, and from the enthalpy change a positive entropy change for the association is indicated. The compounds are disaggregated by concentrated solutions of urea and guanidine hydrochloride. Spectral measurements on the β-glucoside compound indicate disaggregation by sodium dodecyl sulfate above the critical micelle concentration.

scholarly journals A comparative study on the extraction effects of common agents on collagen-based binders in mural paintings

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Jianghao Du ◽  
Zhanyun Zhu ◽  
Junchang Yang ◽  
Jia Wang ◽  
Xiaotong Jiang
Keyword(s):  
Protein Structure ◽  
Comparative Study ◽  
Protein Extraction ◽  
Guanidine Hydrochloride ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Extraction Process ◽  
Ultraviolet Absorption Spectrum ◽  
Mural Paintings ◽  
The Impact

AbstractIn this paper, a comparative study was conducted on the extraction effects of six agents for collagen-based mural painting binders. These agents were used to extract the residual proteins in the non-aged and thermal aged samples. The protein extraction efficiencies of different extracting agents were quantitatively determined by bicinchoninic acid (BCA) method, and then processed by multivariate analysis of variance (MANOVA). The impact of the extraction process on the protein structure was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), ultraviolet absorption spectrum (UV) and circular dichroism (CD). The results showed that, for both non-aged and aged samples, the extraction efficiency of 2 M guanidine hydrochloride (GuHCl) was significantly higher than the other five agents, with less damage to the protein structure during the extraction process.

The interaction of bovine milk caseins with the detergent sodium dodecyl sulphate. II. The effect of detergent binding on spectral properties of caseins

1970 ◽  
Vol 37 (2) ◽  
pp. 259-267 ◽  
Author(s):  
G. C. Cheeseman ◽  
Dorothy J. Knight
Keyword(s):  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Bovine Milk ◽  
Difference Spectrum ◽  
Temperature Dependent ◽  
Difference Spectra ◽  
Negative Change ◽  
Tryptophan Residues ◽  
Hydrophobic Binding ◽  
The Difference

SummaryThe dissociation of casein aggregates by the detergent sodium dodecyl sulphate (SDS) gave rise to difference spectra and these spectra were characteristic for each of the different types of casein. Increase in absorption by the chromophore groups, tyrosine and tryptophan, when αs1- and β-casein aggregates were dissociated indicated binding of the detergent at regions of the molecule containing these residues. A decrease in absorption when κ-casein was dissociated indicated that the tyrosine and tryptophan residues were not in the region of the molecule to which the detergent was bound and that in the κ-casein aggregate these residues were in a more hydrophobic environment. Peaks on the difference spectra were obtained at 280 and 288 nm for αs1-casein and 284 and 291 nm for β-casein and troughs at 278 and 286 nm for κ-casein. The difference spectrum reached a maximum value when the αsl- and β-casein aggregates were dissociated and the further binding of SDS did not alter this value. The large negative change in the difference spectrum of κ-casein did not occur until after most of the aggregates were dissociated and did not reach a maximum until binding with SDS was complete. The value obtained for ΔOD was found to be temperature-dependent for β-casein-SDS interaction, but not for αs1- and κ-casein. Changes in spectra were also observed when αs1- and κ-casein interacted to form aggregates. The data obtained confirmed the importance of hydrophobic binding in casein aggregate formation and indicated the possible involvement of tyrosine and tryptophan residues in this binding.

Vacuum ultraviolet absorption spectrum of p-benzoquinone

1986 ◽  
Vol 82 (3) ◽  
pp. 367 ◽  
Author(s):  
Paul Brint ◽  
Jean-Patrick Connerade ◽  
Pericles Tsekeris ◽  
Agisilaos Bolovinos ◽  
Aslam Baig
Keyword(s):  
Absorption Spectrum ◽  
Vacuum Ultraviolet ◽  
Ultraviolet Absorption ◽  
Ultraviolet Absorption Spectrum
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