Study of the rate of hydrolysis of ethylenimino derivatives of phosphorus acids and the stability of their aqueous alcohol solutions at various pH values

1972 ◽  
Vol 6 (7) ◽  
pp. 475-477 ◽  
Author(s):  
L. D. Protsenko
Keyword(s):  
Aqueous Alcohol ◽  
Ph Values ◽  
Aqueous Alcohol Solutions ◽  
Rate Of Hydrolysis ◽  
The Stability ◽  
Hydrolysis Of ◽  
Derivatives Of

scholarly journals Phosphatase synthesis in Klebsiella (Aerobacter) aerogenes growing in continuous culture

1972 ◽  
Vol 127 (1) ◽  
pp. 87-96 ◽  
Author(s):  
P. G. Bolton ◽  
A. C. R. Dean
Keyword(s):  
Alkaline Phosphatase ◽  
Acid Phosphatase ◽  
Continuous Culture ◽  
Activity Profile ◽  
Glucose Effect ◽  
Ph Values ◽  
Nitrophenyl Phosphate ◽  
Wide Range ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

1. Phosphatase synthesis was studied in Klebsiella aerogenes grown in a wide range of continuous-culture systems. 2. Maximum acid phosphatase synthesis was associated with nutrient-limited, particularly carbohydrate-limited, growth at a relatively low rate, glucose-limited cells exhibiting the highest activity. Compared with glucose as the carbon-limiting growth material, other sugars not only altered the activity but also changed the pH–activity profile of the enzyme(s). 3. The affinity of the acid phosphatase in glucose-limited cells towards p-nitrophenyl phosphate (Km 0.25–0.43mm) was similar to that of staphylococcal acid phosphatase but was ten times greater than that of the Escherichia coli enzyme. 4. PO43−-limitation derepressed alkaline phosphatase synthesis but the amounts of activity were largely independent of the carbon source used for growth. 5. The enzymes were further differentiated by the effect of adding inhibitors (F−, PO43−) and sugars to the reaction mixture during the assays. In particular, it was shown that adding glucose, but not other sugars, stimulated the rate of hydrolysis of p-nitrophenyl phosphate by the acid phosphatase in carbohydrate-limited cells at low pH values (<4.6) but inhibited it at high pH values (>4.6). Alkaline phosphatase activity was unaffected. 6. The function of phosphatases in general is discussed and possible mechanisms for the glucose effect are outlined.

Study and modeling of mechanisms of cholinesterasis reactions in order to improve their catalytic properties in the neutralization reactions of organophosphorous compounds

2020 ◽  
pp. 134-174
Author(s):  
Sergey Varfolomeev ◽  
Bella Grigorenko ◽  
Sofya Lushchekina ◽  
Patrick Masson ◽  
Galina Mahaeva ◽  
...  
Keyword(s):  
First Generation ◽  
Organophosphorus Compounds ◽  
Protein Molecule ◽  
Catalytic Antibodies ◽  
High Rate ◽  
Biological Targets ◽  
Organophosphorous Compounds ◽  
Rate Of Hydrolysis ◽  
The Stability ◽  
Hydrolysis Of

“Biocleaners” or “bioscavengers” are biological objects (enzymes, catalytic antibodies) that are capable of binding and/or hydrolyzing organophosphorus compounds (OPC). Their use seems to be the most effective alternative to traditional antidotes to neutralize or detoxify OPC. The introduction of bioscavengers allows neutralizing toxicant molecules in the bloodstream before they reach their biological targets, thereby providing protection against poisoning. Bioscavengers of the first-generation neutralized OPC molecules by stoichiometrically binding to them. The safety and efficacy of human butyrylcholinesterase (BChE) for protecting against OPC poisoning has been shown. However, the stoichiometric neutralization of OPC requires the introduction of a huge amount of expensive biopharmaceuticals. Catalytic bioscavengers that hydrolytically neutralize OPC were introduced at a much lower dose to achieve the same degree of effectiveness. The most effective catalytic bioscavengers are enzymes. The most promising enzymes are artificial mammalian paraoxonase mutants and bacterial phosphotriesterases. However, studies of other enzymes, such as prolidases, oxidases, artificial mutants of cholinesterases and carboxyl esterases and catalytic antibodies are actively ongoing. Since OPC are pseudosubstrates of cholinesterases (ChEs), a detailed description of the mechanisms of inhibition, dealkylation, and spontaneous reactivation of phosphorylated ChEs is critical for the development of ChEs mutants with a high rate of hydrolysis of OPC. The review presents an analysis of different views on the mechanisms of interaction of ChEs with OPC, discusses the possible directions of creating effective catalytic biological traps based on BChE and changes in their mechanism of action as compared to the native enzyme. A separate section is devoted to the effect of mutations, both polymorphic and artificial, on the stability of the protein molecule of BChE.

scholarly journals Studies on the preparation of water-insoluble derivatives of rennin and chymotrypsin and their use in the hydrolysis of casein and the clotting of milk

1969 ◽  
Vol 115 (2) ◽  
pp. 183-190 ◽  
Author(s):  
Margaret L. Green ◽  
G. Crutchfield
Keyword(s):  
Continuous System ◽  
Competitive Inhibitor ◽  
Active Enzyme ◽  
Ph Values ◽  
Hydrolysis Of ◽  
Derivatives Of

1. Enzymically active insoluble derivatives of chymotrypsin and rennin were prepared by coupling each enzyme to agarose as described by Porath, Axén & Ernback (1967) and rennin to aminoethylcellulose by the method of Habeeb (1967). 2. Agarose–chymotrypsin was stable over the range pH2–9, but agarose–rennin released active enzyme into solution at above pH2 and aminoethylcellulose–rennin was similarly unstable at certain pH values. 3. Each derivative appeared to catalyse the clotting of milk at 30°, but this was probably entirely due to enzyme released into solution from the carrier. 4. The presence of a competitive inhibitor of chymotrypsin during its coupling to agarose had no effect on the activity or stability of the resulting derivative. 5. The characteristics of agarose and cellulose render them not entirely suitable for use in a continuous system with milk.

scholarly journals Stability of unimolecular films of 32P-labelled lecithin

1967 ◽  
Vol 105 (1) ◽  
pp. 401-407 ◽  
Author(s):  
H. Hauser ◽  
R. M. C. Dawson
Keyword(s):  
Pressure Change ◽  
Ion Concentration ◽  
Hydrolysis Rate ◽  
Ion Distribution ◽  
Rapid Perfusion ◽  
Poisson Boltzmann ◽  
Rate Of Hydrolysis ◽  
Poisson Boltzmann Equation ◽  
The Stability ◽  
Hydrolysis Of

1. The stability of monolayers of a highly unsaturated yeast lecithin labelled with 32P has been investigated by a surface radioactivity technique. 2. Lecithin films on distilled water at all surface pressures between 6 and 48dynes/cm. were completely stable on rapid perfusion of the subphase and on addition of ionic amphipathic substances to the film. 3. Ultrasonically treated lecithin added to the subphase caused a slow loss of surface radioactivity but little pressure change. 4. The addition of proteins to the subphase caused negligible changes in the film even when conditions were favourable for electrostatic heterocoagulation and penetration. 5. Lecithin films were not hydrolysed by a strongly acid subphase at room temperature. The very low rate of hydrolysis produced by alkali was proportional to the subphase OH−ion concentration: the apparent activation energy and temperature coefficient (Q10) of the reaction were 14250 cal. and 2·37 respectively. 6. Alkaline hydrolysis of lecithin monolayers was markedly stimulated by adding methanol (10–20%, v/v) to the subphase. The addition of ionic amphipaths to the monolayer had the expected type of effect on the hydrolysis rate, but its magnitude was far less than that suggested by an application of the Poisson–Boltzmann equation for ion distribution at a charged interface (Davies & Rideal, 1963).

DERIVATIVES OF DEHYDROABIETIC AND PODOCARPIC ACIDS

1963 ◽  
Vol 41 (8) ◽  
pp. 1924-1936 ◽  
Author(s):  
Ernest Wenkert ◽  
Peter Beak ◽  
Richard W. J. Carney ◽  
James W. Chamberlin ◽  
David B. R. Johnston ◽  
...  
Keyword(s):  
Methyl Esters ◽  
Resin Acid ◽  
Aluminum Hydride ◽  
Resin Acids ◽  
Lithium Aluminum ◽  
Hydride Reduction ◽  
Rate Of Hydrolysis ◽  
Keto Derivative ◽  
Hydrolysis Of ◽  
Derivatives Of

The lithium aluminum hydride reduction of nitriles in the aromatic resin acid series to aldimines and the conversion of the products to other derivatives are described. The effect of the stereochemistry of the nitriles on the rate of reduction is noted. The transformation of dehydroabietane into a dehydro product is indicated. The syntheses of a desoxydecarboxy-5,6-dehydro-7-keto derivative of podocarpic acid and its optical antipode are discussed. The stereochemistry of hydrogenation of 5,6-dehydro derivatives of podocarpic acid is reported. The effect of a 7-keto group on the rate of hydrolysis of methyl esters of aromatic resin acids is illustrated. The reactions of 6-bromo-7-keto derivatives of methyl podocarpate with bases are portrayed.

A study of the hydrolysis of amino derivatives of gossypol at various pH values

1999 ◽  
Vol 35 (1) ◽  
pp. 29-32 ◽  
Author(s):  
N. I. Baram ◽  
Kh. L. Ziyaev ◽  
B. Khodzhaniyazov ◽  
A. I. Ismailov
Keyword(s):  
Ph Values ◽  
Amino Derivatives ◽  
Hydrolysis Of ◽  
Derivatives Of

scholarly journals EFFECT OF PH ON THE STABILITY OF COORDINATION COMPOUNDS OF CO(III) WITH DIAMINOETHANOL LIGANDS IN NON-AQUEOUS SOLUTIONS

2020 ◽  
Vol 2 (61) ◽  
pp. 119-127
Author(s):  
I. Kuzevanova ◽  
◽  
S. Povalchyk ◽  
A. Zulfigarov ◽  
A. Andriiko ◽  
...  
Keyword(s):  
Complex Compound ◽  
Coordination Compounds ◽  
Ph Value ◽  
Precursor Solution ◽  
Polynuclear Complex ◽  
Alkaline Solutions ◽  
Partial Hydrolysis ◽  
Ph Values ◽  
The Stability ◽  
Hydrolysis Of

Inner complex compound of cobalt(III) with diaminoethanol, [Co(DetmHdetm)], and polynuclear complex compound 2Co-Ni with diaminoethanol, [Ni(CoDetmHdetm)2](NO3)2, were synthesized. Stabilities of the obtained compounds were investigated in non-aqueous (dimethylformamide) solutions at different values of pH (from acid to alkaline). Methods of potentiometric titration and electron absorption spectra were used to determine the range of pH values where the compounds do not decompose. As a result of these studies, we found that at the upper value of pH=7, the coordination surrounding of the metals (Co(III), Ni(II)) does not change. When the pH value becomes lower than 7 (with adding HCl acide), the inner complex of Co(III) begins to decompose. The ligand H2detm is replaced by Cland partial protonization of diethanolamine occurs. Also, transformation of N,Ncis isomer of inner complex compound of cobalt(III) to N,N-trans isomer takes place, thus reducing the symmetry of the complex. As for the polynuclear complex compound 2Co-Ni, when pH value becomes lower than 7, molecules of solvent begin to react with the products of partially destroyed complex. As a result, new complex compound is formed with the increase of coordination number of nickel(II) from 4 to 6. However, in alkaline solutions where pH values are up to 10, the heterometal complex compound of 2Co-Ni remains stable. Only partial hydrolysis of the solvent occurs in these conditions. The schemes of transformations of [Co(DetmHdetm)] and [Ni(CoDetmHdetm)2](NO3)2 occuring in non-aqueous (dimethylformamide) solutions at different values of pH (from acid to alkaline) are presented in the paper. The results of this study can be used for the preparation of precursor solution for the technology of catalytic materials production. Evidently, the range of pH from 7 to 10 must be maintained in order to avoid the contamination of the final products by the decomposed wastes of complexes and solvent.

scholarly journals Synthesis of Biopolymers by Condensed Histidine Imide Derivatives with Some Acid Anhydride and Their Crosslink with Acrylonitrite

2014 ◽  
Vol 5 (1) ◽  
pp. 27-41
Author(s):  
Dr. Firyal. M.A ◽  
Assel K. M.
Keyword(s):  
Chemical Resistance ◽  
Basic Medium ◽  
Direct Polycondensation ◽  
Visible Spectroscopy ◽  
Bioactive Polymers ◽  
Ph Values ◽  
Ft Ir ◽  
Rate Of Hydrolysis ◽  
Uv Visible ◽  
Hydrolysis Of

Histidine as known amino acid was converted to its acid chloride [C1] with thionyl chloride at 0 oC, then reacted with ammonia, the corresponding imide-diamine [C2] was obtained, and then condensed with maleic or methylnadic anhydride. The two novel condensed polymers [C3, C4] were obtained with highly conversion percentage and modified to crosslinked polymers [C5, C6] with acrylonitrile monomer through vinylic group by free radical polymerization. The physical properties of all prepared polymers were studied and characterized by 1H-NMR, FT-IR and UV-visible spectroscopy. The swelling % was calculated. The new Polymers [C3, C4], were synthesized by direct polycondensation to give the new bioactive polymers. The rate of hydrolysis of the prepared polymers was studied in different pH values at 37 oC. Howeve, the crosslinked biopolymers [C5, C6] indicated much more chemical resistance than [C3, C4], and the sustained release was observed as good results in basic medium.

EFFECT OF pH, CALCIUM CONCENTRATION AND TEMPERATURE ON THE HYDROLYSIS OF DICALCIUM PHOSPHATE DIHYDRATE

1989 ◽  
Vol 69 (3) ◽  
pp. 689-693 ◽  
Author(s):  
G. W. MORDEN ◽  
G. J. RACZ
Keyword(s):  
Key Words ◽  
Calcium Concentration ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Effect Of Ph ◽  
Ph Values ◽  
Phosphate Dihydrate ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The rate of hydrolysis of DCPD to OCP in solutions of different pH values, calcium concentrations and temperatures was studied. Rates of hydrolysis were very slow at pH 6.0, relatively rapid and similar at pH 7.0 and 8.0, much slower at 10 °C than at 20 or 30 °C, and only slightly increased by increasing calcium concentration. Key words: Dicalcium phosphate dihydrate, hydrolysis, pH, temperature, calcium concentration

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