scholarly journals Some changes in the reactivity of enzymes resulting from their chemical attachment to water-insoluble derivatives of cellulose

1968 ◽  
Vol 107 (5) ◽  
pp. 669-674 ◽  
Author(s):  
W. E. Hornby ◽  
M. D. Lilly ◽  
E. M. Crook
Keyword(s):  
Ionic Strength ◽  
Electrostatic Interaction ◽  
Nitrobenzoic Acid ◽  
Enzyme Substrates ◽  
Derivatives Of

1. Purified ficin was chemically attached to CM-cellulose, and partially purified ATP–creatine phosphotransferase was chemically attached to both CM-cellulose and p-aminobenzylcellulose. 2. The apparent Km with respect to ATP and Mg2+ of ATP–creatine phosphotransferase was observed to increase about tenfold on attachment of the enzyme to CM-cellulose, and to increase by only 23% on its attachment to p-aminobenzylcellulose. 3. The reactivity of both ficin and ATP–creatine phosphotransferase with 5,5′-dithiobis-(2-nitrobenzoic acid) was observed to decrease on chemical attachment of these enzymes to water-insoluble derivatives of cellulose. With derivatives prepared from CM-cellulose, the extent of the reaction with 5,5′-dithiobis-(2-nitrobenzoic acid) was dependent on ionic strength, but with similar derivatives prepared from p-aminobenzylcellulose the extent of this reaction was independent of ionic strength. 4. The effect of diffusion and electrostatic interaction of charged enzyme substrates and charged enzyme supports on the apparent Km of a water-insoluble derivative of an enzyme is discussed. An equation is derived that satisfactorily describes the observed effects of these factors on the apparent Km.

The Interactions of adenylates with allosteric citrate synthase

1979 ◽  
Vol 57 (5) ◽  
pp. 385-395 ◽  
Author(s):  
Michael M. Talgoy ◽  
Harry W. Duckworth
Keyword(s):  
Coenzyme A ◽  
Citrate Synthase ◽  
Potent Inhibitor ◽  
Sulfhydryl Group ◽  
Fluorescence Technique ◽  
Allosteric Site ◽  
Acetyl Coenzyme A ◽  
Nitrobenzoic Acid ◽  
Adenylic Acid ◽  
Derivatives Of

Evidence is presented that a number of derivatives of adenylic acid may bind to the allosteric NADH binding site of Escherichia coli citrate synthase. This evidence includes the facts that all the adenylates inhibit NADH binding in a competitive manner and that those which have been tested protect an enzyme sulfhydryl group from reaction with 5,5′-dithiobis-(2-nitrobenzoic acid) in the same way that NADH does. However, whereas NADH is a potent inhibitor of citrate synthase, most of the adenylates are activators. The best activator, ADP-ribose, increases the affinity of the enzyme for the substrate, acetyl-CoA, and saturates the enzyme in a sigmoid manner. A fluorescence technique, involving the displacement of 8-anilino-1-naphthalenesulfonate from its complex with citrate synthase, is used to obtain saturation curves for several nucleotides under nonassay conditions. It is found that acetyl-coenzyme A, coenzyme A, and ADP-ribose all bind to the enzyme cooperatively, and that the binding of each becomes tighter in the presence of KCl the activator, and oxaloacetic acid (OAA), the second substrate. Another inhibitor, α-ketoglutarate, can compete with OAA in the absence of KClbut not in its presence. The nature of the allosteric site of citrate synthase, and the modes of action of several activators and inhibitors, are discussed in the light of this evidence.

scholarly journals Adjacent cationic–aromatic sequences yield strong electrostatic adhesion of hydrogels in seawater

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Hailong Fan ◽  
Jiahui Wang ◽  
Zhen Tao ◽  
Junchao Huang ◽  
Ping Rao ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
Saline Water ◽  
Aromatic Amino Acids ◽  
High Ionic Strength ◽  
Polymer Materials ◽  
Specific Sequence ◽  
Charged Surfaces ◽  
Π Complex

Abstract Electrostatic interaction is strong but usually diminishes in high ionic-strength environments. Biosystems can use this interaction through adjacent cationic–aromatic amino acids sequence of proteins even in a saline medium. Application of such specific sequence to the development of cationic polymer materials adhesive to negatively charged surfaces in saline environments is challenging due to the difficulty in controlling the copolymer sequences. Here, we discover that copolymers with adjacent cation–aromatic sequences can be synthesized through cation–π complex-aided free-radical polymerization. Sequence controlled hydrogels from diverse cation/aromatic monomers exhibit fast, strong but reversible adhesion to negatively charged surfaces in seawater. Aromatics on copolymers are found to enhance the electrostatic interactions of their adjacent cationic residues to the counter surfaces, even in a high ionic-strength medium that screens the electrostatic interaction for common polyelectrolytes. This work opens a pathway to develop adhesives using saline water.

scholarly journals The possibility of using silochrome sorbents for proteinase inhibitor aprotinin

2020 ◽  
pp. 13-14
Author(s):  
O.G. Braginets ◽  
V.V. Ivasyk ◽  
B.O. Kondratskyi ◽  
D.L. Kachmaryk ◽  
V.L. Novak
Keyword(s):  
Ionic Strength ◽  
Electrostatic Interaction ◽  
Proteinase Inhibitor ◽  
Large Scale ◽  
Hydrophobic Interactions ◽  
High Capacity ◽  
Peristaltic Pump ◽  
Chromatographic Purification ◽  
Original Matrix ◽  
Bright Blue

Background. Aprotinin is a polypeptide, a proteinase inhibitor of natural origin. It inhibits kallikrein, kininogenase, plasmin, trypsin, chymotrypsin; blocks the activator of profibrinolysin, which helps to stop bleeding. Aprotinin is obtained from the lungs of cattle. Objective. To study the sorption of aprotinin on silochromic sorbents. Materials and methods. Affinity sorbents based on silochrome were used in the work: p-chlorobenzyl-silochrome, active bright blue K-silochrome, aminopropyl silochrome, phenyl-diol-silochrome, phenyl-glutaryl-silochrome. The optical density was measured on KFK-3 (590 nm, 750 nm) and SF-46 (280 nm). An NP-3 peristaltic pump was used for chromatographic purification. Results and discussion. Based on the obtained data, it can be assumed that the mechanism of binding of aprotinin to all carriers is obviously the same and is based on the presence of hydrophobic sites in its molecule, which leads to hydrophobic interactions with sorbents. However, increasing the hydrophobicity of the eluent does not lead to desorption of the inhibitor. Obviously, in addition to hydrophobic, a significant role is played by the electrostatic interaction, which is eliminated by increasing the ionic strength. The sorbents under study have a high capacity, they do not change their volume when the ionic strength or hydrophobicity changes, and therefore may be suitable for large-scale applications. Conclusions. Affinity sorbents based on silochrome, containing as ligands aminobenzene, p-chlorobenzyl chloride and active chlorotriazine dye of the anthraquinone series “active bright blue K”, in contrast to the original matrix – silochrome aminopropyl water and effectively dissolve. Increasing the ionic strength or hydrophobicity of desorbing solutions does not lead to elution of aprotinin due to additional electrostatic interaction. Therefore, the desorption of aprotinin is achieved only if it is eliminated in the presence of 25 % isopropanol with 1M NaCl.

Effect of the concentration of 5,5'-dithiobis(2-nitrobenzoic acid) on parameters of the kinetics of its chemisorption on thiol derivatives of cellulose

1986 ◽  
Vol 51 (3) ◽  
pp. 545-552 ◽  
Author(s):  
Albert Breier ◽  
Peter Gemeiner ◽  
Milan J. Beneš
Keyword(s):  
Ethyl Cellulose ◽  
Chemical Structure ◽  
Sorption Process ◽  
Sorption Kinetics ◽  
Cellulose Derivatives ◽  
Experimental Conditions ◽  
Nitrobenzoic Acid ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Sorbate Concentration

Equations describing the dependence of parameters of sorption kinetics on the sorbate concentration have been determined. The validity of the equations has been verified for the chemisorption of 5,5'-dithiobis(2-nitrobenzoic acid) on bead O-(2-mercaptoethyl)-, O-(3-mercapto-2-hydroxy-propyl)- and O-[2-(4-mercaptophenylsulfonyl)ethyl]cellulose. Isothermic constants obtained from the equations can be calculated also under experimental conditions unfavourable for their determination. These constants may be utilized for characterizing relations between the chemical structure of cellulose derivatives and the sorption process. The equation which provides a complete time-concentration description of sorption is suggested.

scholarly journals Intermolecular Interactions in Polyelectrolyte and Surfactant Complexes in Solution

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 51 ◽  
Author(s):  
Nasreen Khan ◽  
Blair Brettmann
Keyword(s):  
Ionic Strength ◽  
Charge Density ◽  
Unique Solution ◽  
Electrostatic Interaction ◽  
Molecular Interaction ◽  
Electrostatic Interactions ◽  
Molecular Level ◽  
Polymeric Materials ◽  
Bulk Solution ◽  
Important Class

Polyelectrolytes are an important class of polymeric materials and are increasingly used in complex industrial formulations. A core use of these materials is in mixtures with surfactants, where a combination of hydrophobic and electrostatic interactions drives unique solution behavior and structure formation. In this review, we apply a molecular level perspective to the broad literature on polyelectrolyte-surfactant complexes, discussing explicitly the hydrophobic and electrostatic interaction contributions to polyelectrolyte surfactant complexes (PESCs), as well as the interplay between the two molecular interaction types. These interactions are sensitive to a variety of solution conditions, such as pH, ionic strength, mixing procedure, charge density, etc. and these parameters can readily be used to control the concentration at which structures form as well as the type of structure in the bulk solution.

Mechanism of the oxidation of triphenyl derivatives of P, As, and Sb by peroxodiphosphate

1985 ◽  
Vol 63 (8) ◽  
pp. 2285-2289 ◽  
Author(s):  
C. Srinivasan ◽  
K. Pitchumani
Keyword(s):  
Ionic Strength ◽  
Reaction Rate ◽  
Relative Rate ◽  
Active Species ◽  
Second Order ◽  
Rate Coefficients ◽  
General Mechanism ◽  
First Order ◽  
Nucleophilic Displacement ◽  
Derivatives Of

Rate coefficients have been determined for the oxidation of Ph3M (M = P, As, Sb) by potassium peroxodiphosphate. The reaction is found to follow second-order kinetics, first order in each in the oxidant and Ph3M. [H+] has a pronounced accelerating effect on the reaction rate. An interesting dependence of the active species on the nature of the substrate has been observed. The reaction rate is influenced by changing the ionic strength of the medium. Acrylonitrile has no effect on the rate of oxidation. On the basis of the kinetic evidence, a general mechanism involving a biomolecular nucleophilic displacement of the substrate on the peroxo ion has been proposed. The relative rate order is found to be Ph3P > Ph3Sb > Ph3As and an explanation has been offered for the transposition of Ph3Sb and Ph3As.

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