scholarly journals SYNTHESIS AND PROPERTIES OF MODEL SYSTEMS, WITH THEIR USE IN STUDYING THE SCHIFF REACTION IN HISTOCHEMISTRY

1964 ◽  
Vol 12 (7) ◽  
pp. 533-537 ◽  
Author(s):  
M. J. HARDONK ◽  
P. VAN DUIJN
Keyword(s):  
Sulfhydryl Groups ◽  
Phosphate Group ◽  
Model Systems ◽  
Cellulose Derivatives ◽  
Amino Groups ◽  
Cellulose Films ◽  
Reactive Groups ◽  
Schiff Reaction ◽  
Cellulose Membranes ◽  
Covalently Bound

The synthesis of cellulose films containing several reactive groups is described. These films were developed for use as histochemical model systems to study several Schiff-type reactions. The synthesized model systems include cellulose membranes to which amino groups are covalently bound, cellulose membranes containing sulfhydryl groups, and cellulose membranes to which deoxyribonucleotides have been bound by means of their phosphate group. Evidence is given for the structure of these cellulose derivatives.

scholarly journals STUDIES ON THE FEULGEN REACTION WITH HISTOCHEMICAL MODEL SYSTEMS

1964 ◽  
Vol 12 (10) ◽  
pp. 758-767 ◽  
Author(s):  
M. J. HARDONK ◽  
P. VAN DUIJN
Keyword(s):  
Crystal Violet ◽  
Deoxyribonucleic Acid ◽  
Spectral Shift ◽  
The Other ◽  
Model Systems ◽  
Cellulose Film ◽  
Feulgen Reaction ◽  
Cell Nuclei ◽  
Amino Groups ◽  
Schiff Reaction

The absorption spectra of Feulgen-stained deoxyribonucleic acid (DNA)-containing membranes have been studied under various conditions. The absorption curve of the Feulgen-stained DNA-cellulose differs from those of the other model systems and is comparable to that of a solution of apurinic acid stained by the Schiff reaction. The spectral shift caused by the reaction of formaldehyde and SO2 with the stained films was used as a criterion for the degree of substitution of the bound pararosaniline. The spectrum of DNA-cellulose, unlike the spectra of the other models, did not show any change under the action of these reagents. This indicates that the three amino groups of pararosaniline are all bound to the DNA in a stained DNA-cellulose film. When the mobility of the apurinic acid chain is restricted, the formation of the trisubstituted product is apparently hindered. Such a situation may be present in DNA-containing polyacrylamide films containing proteins and also in cell nuclei. From a study of the literature it is concluded that the shoulder in the pararosaniline spectrum is most probably caused by a configurational isomer of the dye as indicated by Lewis et al. (16) for crystal violet. To explain the abnormal spectrum of the stained DNA-cellulose, it is proposed that in this case pararosaniline is bound with the three amino groups to three neighbouring deoxyribose groups in the hydrolyzed DNA. Studies with Stuart models of the molecules involved showed that in this case one conformation isomer of pararosaniline can be constructed more easily than the other. This situation may explain the spectrum of the stained DNA-cellulose. The other spectral results could also be interpreted on basis of this hypothesis.

scholarly journals THE SPECIFICITY OF KERATEINE DERIVATIVES

1939 ◽  
Vol 70 (4) ◽  
pp. 387-397 ◽  
Author(s):  
L. Pillemer ◽  
E. E. Ecker ◽  
E. W. Martiensen
Keyword(s):  
Chemical Analysis ◽  
Free Amino ◽  
Sulfhydryl Groups ◽  
Amino Groups ◽  
Substituent Group ◽  
Parent Protein ◽  
Isoelectric Points

Carboxymethyl, α-carboxyethyl-, α-carboxy-n-propyl-, α-carboxyisopropyl-, α-carboxy-n-butyl, α-carboxyisobutyl, α-carboxyamyl-, benzyl-, and ß-phenylethylkeratemes were prepared from the parent protein, reduced keratin or kerateine. Chemical analysis disclosed that the various compounds differed in their isoelectric points and solubilities depending on the nature of the substituent group introduced. In general, it was found that in so far as could be determined, nearly all of the available sulfhydryl groups were substituted, while no detectable substitution of the free amino groups of the proteins occurred. The results of the serologic studies revealed that the kerateine derivatives acquired a new immunologie character dependent on the nature of the introduced determinant group. Inhibition tests confirmed the results obtained. Evidence was also produced to show that the grouping See PDF for structure may play a rôle in some of the reactions observed.

Effect of cross-linking agents on insulin associated responses in adipocytes

1982 ◽  
Vol 60 (10) ◽  
pp. 987-1000 ◽  
Author(s):  
H. Joseph Goren ◽  
C. Ronald Kahn
Keyword(s):  
Insulin Receptor ◽  
Glucose Transport ◽  
Free Amino ◽  
Glucose Oxidation ◽  
Insulin Binding ◽  
Cross Linking ◽  
Amino Group ◽  
Amino Groups ◽  
Disuccinimidyl Suberate ◽  
Reactive Groups

The effect of 10 bifunctional cross-linking agents and four monofunctional analogues was studied on isolated adipocytes. [125I]Insulin binding and degradation, basal and insulin-stimulated glucose oxidation, and 3-O-methyl glucose uptake were measured. Two cross-linkers, which possess succinimide ester residues (disuccinimidyl suberate and dithiobis(succinimidyl propionate)) and react selectively with amino groups, appeared to react relatively specifically with the insulin receptor. Both produced a slight stimulation of basal glucose transport and metabolism, a marked inhibition of insulin-stimulated glucose transport and metabolism, and a marked decrease in insulin binding. Pretreatment of cells with unlabelled insulin partially blocked the effect of disuccinimidyl suberate, and as has been previously shown, disuccinimidyl suberate cross-linked insulin to its receptor. A monofunctional analogue of these compounds was 100-fold less active in altering cellular metabolic activity. Bisimidates, such as dimethyl suberimidate, dimethyl adipimidate, and dimethyl dithiobispropionimidate, also react with free amino groups but are more hydrophilic. These agents produced similar effects on glucose oxidation as the succinimide esters, but had little or no effect on insulin binding. The effects of these agents are not blocked by insulin and they do not cross-link insulin to its receptor. Mixed bifunctional reagents containing either a succinimide ester or an imidate and a group which reacts with thiols produced effects similar to the cross-linkers containing two succinimide groups or bisimidates, respectively. The bifunctional arylating agents difluorodinitrobenzene and bis(fluoronitrophenyl)sulfone produce marked effects on insulin binding and glucose oxidation at micromolar concentrations, but the monofunctional analogue fluorodinitrobenzene is almost equally active suggesting that with these compounds chemical modifications and not cross-linking was important. With neither the mixed bifunctional reagents, nor the arylating agents, did insulin pretreatment alter the effect of cross-linker and none of these agents cross-linked [125I]insulin to its receptor. These data suggest that the insulin receptor possesses a free amino group in a hydrophobic environment in its active site. A reactive amino group in a hydrophilic environment as well as other reactive groups are also present in some component of the insulin receptor–effector complex. Chemical modification or cross-linking of these functional groups results in an inhibition or mimicking of insulin action. Further study will be required to identify the exact locus of these sites.

Cellulose-based polymers

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Xing Zhou ◽  
Yaya Hao ◽  
Xin Zhang ◽  
Xinyu He ◽  
Chaoqun Zhang
Keyword(s):  
Smart Materials ◽  
Industrial Production ◽  
Cellulose Fibers ◽  
Cellulose Derivatives ◽  
Structure And Properties ◽  
Significant Progress ◽  
Main Attention ◽  
Environmental Friendly ◽  
Structure Morphology ◽  
Cellulose Membranes

Abstract The presented chapter deals with structure, morphology, and properties aspects concerning cellulose-based polymers in both research and industrial production, such as cellulose fibers, cellulose membranes, cellulose nanocrystals, and bacterial cellulose, etc. The idea was to highlight the main cellulose-based polymers and cellulose derivatives, as well as the dissolution technologies in processing cellulose-based products. The structure and properties of cellulose are introduced briefly. The main attention has been paid to swelling and dissolution of cellulose in order to yield various kinds of cellulose derivatives through polymerization. The main mechanisms and methods are also presented. Finally, the environmental friendly and green cellulose-based polymers will be evaluated as one of the multifunctional and smart materials with significant progress.

Kinetics of the Reaction of Nitrous Acid with Model Compounds and Proteins, and the Conformational State of N-terminal Groups in the Chymotrypsin Family

1972 ◽  
Vol 50 (12) ◽  
pp. 1282-1296 ◽  
Author(s):  
A. Kurosky ◽  
T. Hofmann
Keyword(s):  
Nitrous Acid ◽  
Conformational State ◽  
Serine Proteinases ◽  
Amino Groups ◽  
Model Compounds ◽  
Third Order ◽  
Tyrosine Residues ◽  
Reactive Groups ◽  
Primary Amino ◽  
Kinetics Of

The kinetics of the reaction of nitrous acid at 4° and pH 4.0 with various amino acids, peptides, and proteins were studied. The reaction with isoleucine methyl ester was found to have a linear dependence on the square of the HONO concentration showing that N2O3 was the reactive species. Third order nitrosation rate constants of primary amino groups showed a correlation with their pK values. They were calculated for the concentration of the unprotonated species to give intrinsic reactivities. The rate of nitrosation of acetyltryptophan to give N-nitrosoacetyltryptophan was found to be a linear function of the nitrous acid concentration. This nitrosation therefore follows a different mechanism. The reaction of nitrous acid with tyrosine residues was examined by spectrophotometry. The reaction was negligible compared to that of other groups. Acetylhistidine and imidazole did not react. Reactivities for α-amino groups, ε-amino groups, and other residues in proteins were compared. The conformational state of the N-terminal residues in serine proteinases, as revealed from their reactivities, is discussed in detail. It is concluded that nitrous acid reacts preferentially with "surface" residues and is a useful tool for exploring conformational states of reactive groups in proteins, especially α-amino groups and indole rings.

Experimental and Theoretical Study of the First Vanadocene(IV) Complexes of α-Amino Acids Prepared from Vanadocene Dichloride

2004 ◽  
Vol 69 (4) ◽  
pp. 811-821 ◽  
Author(s):  
Jaromír Vinklárek ◽  
Hana Paláčková ◽  
Jan Honzíček
Keyword(s):  
Amino Acids ◽  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Study ◽  
Model Systems ◽  
Amino Groups ◽  
Aqueous Methanol ◽  
Functional Theory ◽  
Elemental Analyses ◽  
Vanadocene Dichloride

The first bioinorganic vanadocene(IV) complexes of α-amino acids ([Cp2V(aa)]Cl, Cp = η5-C5H5, aa = glycine, L-alanine, L-valine) were prepared by reaction of vanadocene dichloride ([Cp2VCl2]) and α-amino acids in aqueous methanol. Analogous cationic complexes with PF6- counterions were obtained by metathetical reactions of the chloride precursors with KPF6. These compounds are of great interest as model systems for the vanadocene moiety binding to proteins. All complexes have been characterized by elemental analyses and IR, Raman and EPR spectroscopies. On the basis of EPR spectra, a chelate in all the studied complexes was proposed, formed by the carboxylato and amino groups. This structure has also been confirmed by density functional theory (DFT) calculations.

370. The reaction between milk protein and reducing sugar in the ‘dry’ state

1948 ◽  
Vol 15 (3) ◽  
pp. 369-376 ◽  
Author(s):  
C. H. Lea
Keyword(s):  
Relative Humidity ◽  
Free Amino ◽  
Milk Protein ◽  
Reducing Sugars ◽  
Reducing Sugar ◽  
Hot Water ◽  
Prolonged Storage ◽  
Amino Groups ◽  
Reactive Groups

‘Dry’, dialysed milk protein was stored for 6 months at 37° C. and 55% relative humidity alone and in the presence of small proportions of glucose, of high proportions of lactose and of sucrose, and of mixtures of these sugars.The reducing sugars combined with free amino-groups of the protein, apparently in a 1:1 ratio; sucrose did not. The reaction did not proceed to completion, probably owing to difficulty of access of the reactive groups to one another. Only when the sugar-amino reaction occurred did discoloration ensue.Glucose reacted more rapidly with the protein than did lactose, and the complex formed became discoloured and insoluble in both cold and hot water much more rapidly.Sucrose and lactose both greatly delayed the onset of glucose-induced insolubility, lactose being the more efficient of the two. They did not prevent discoloration.The protein alone became insoluble in cold but not in hot water after prolonged storage; but did not discolour. This change was prevented by sucrose. The behaviour of lactose was inconsistent, loss of solubility being accelerated in one experiment and retarded in another.

scholarly journals Carbonyl and sulfhydryl groups of chicken meat proteins after dietary modulation with selenium

2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Małgorzata Korzeniowska ◽  
Bożena Króliczewska ◽  
Wiesław Kopeć
Keyword(s):  
Frozen Storage ◽  
Protein Carbonyl ◽  
Sulfhydryl Groups ◽  
Chicken Breast ◽  
Selenium Compounds ◽  
Reactive Groups ◽  
Protein Sulfhydryl ◽  
Chicken Muscles ◽  
Protein Sulfhydryl Groups ◽  
Induced Changes

AbstractThe objective of the study was to investigate the effects of selenium modulation on the alteration of carbonyl and sulfhydryl groups in proteins in chicken breast and leg meat. Selenium, in the form of sodium selenite and selenized yeast, was applied to broiler chicken at 0.26, 0.38 and 0.50 mg Se kg-1. The alteration of protein carbonyl and sulfhydryl groups, as well as total antioxidative potential of breast and leg meat were analyzed in fresh, chilled and frozen material. Protein reactive groups were effectively protected against oxidatively induced changes (carbonyl groups formation) by dietary selenium supplementation, during frozen storage of both types of chicken muscles, either with white fibre domination (breast) or with red fibre domination (leg). The inorganic form of selenium was effective in decreasing the loss of protein sulfhydryl groups in muscles with red fibre domination during frozen storage. In conclusion, selenium compounds can be used in broiler nutrition as a protein antioxidizing agent, especially in perspective of the long storage of meat under freezing conditions.

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