Formation of hybrid colloids by suspension polycondensation in the presence of hydrophilic block copolymers

AbstractDouble hydrophilic block copolymers were used to control the growth of inorganic particles and directly prepare hybrid colloidal suspensions. Colloids of metal hydrous oxides were obtained by forced hydrolysis of metal ions in presence of the copolymers. The block copolymers contain a metal-complexing polyelectrolyte block and a stabilizing neutral block. The role of the first block is to ensure a controlled growth of the inorganic phase, while simultaneously, the second block ensures the colloidal stabilization. Phase diagrams presenting the conditions under which precipitation is inhibited are established. The nanoparticles are then characterized in terms of sizes, morphologies and surface charges. The main parameters controlling the size were identified: the copolymer-to-metal ratio and the metal prehydrolysis ratio. The synthesis steps were characterized. First, a key step of induced micellization of the hydrophilic copolymers leads to hybrid core-shell assemblies. The second step consists in mineralization of the micellar core. The suspension polycondensation leads to hairy particles whose morphologies depend on the nature of the metal and on synthesis parameters.

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Role of a guanine nucleotide-binding regulatory protein in the hydrolysis of hepatocyte phosphatidylinositol 4,5-bisphosphate by calcium-mobilizing hormones and the control of cell calcium. Studies utilizing aluminum fluoride.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)38594-0 ◽

1985 ◽

Vol 260 (27) ◽

pp. 14477-14483 ◽

Cited By ~ 33

Author(s):

P F Blackmore ◽

S B Bocckino ◽

L E Waynick ◽

J H Exton

Keyword(s):

Regulatory Protein ◽

Nucleotide Binding ◽

Aluminum Fluoride ◽

Guanine Nucleotide ◽

Cell Calcium ◽

Guanine Nucleotide Binding ◽

Hydrolysis Of

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The role of collective elasticity on activated structural relaxation, yielding, and steady state flow in hard sphere fluids and colloidal suspensions under strong deformation

The Journal of Chemical Physics ◽

10.1063/5.0026258 ◽

2020 ◽

Vol 153 (19) ◽

pp. 194502

Author(s):

Ashesh Ghosh ◽

Kenneth S. Schweizer

Keyword(s):

Steady State ◽

Structural Relaxation ◽

Hard Sphere ◽

Colloidal Suspensions ◽

Steady State Flow ◽

State Flow ◽

Strong Deformation

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Steroid Sulphatase and Its Inhibitors: Past, Present and Future

Molecules ◽

10.3390/molecules26102852 ◽

2021 ◽

Vol 26 (10) ◽

pp. 2852

Author(s):

Paul A. Foster

Keyword(s):

Good Evidence ◽

The Past ◽

Steroid Sulphatase ◽

University Of Oxford ◽

Therapeutic Value ◽

Breast And Prostate Cancer ◽

The University ◽

Further Development ◽

Hydrolysis Of

Steroid sulphatase (STS), involved in the hydrolysis of steroid sulphates, plays an important role in the formation of both active oestrogens and androgens. Since these steroids significantly impact the proliferation of both oestrogen- and androgen-dependent cancers, many research groups over the past 30 years have designed and developed STS inhibitors. One of the main contributors to this field has been Prof. Barry Potter, previously at the University of Bath and now at the University of Oxford. Upon Prof. Potter’s imminent retirement, this review takes a look back at the work on STS inhibitors and their contribution to our understanding of sulphate biology and as potential therapeutic agents in hormone-dependent disease. A number of potent STS inhibitors have now been developed, one of which, Irosustat (STX64, 667Coumate, BN83495), remains the only one to have completed phase I/II clinical trials against numerous indications (breast, prostate, endometrial). These studies have provided new insights into the origins of androgens and oestrogens in women and men. In addition to the therapeutic role of STS inhibition in breast and prostate cancer, there is now good evidence to suggest they may also provide benefits in patients with colorectal and ovarian cancer, and in treating endometriosis. To explore the potential of STS inhibitors further, a number of second- and third-generation inhibitors have been developed, together with single molecules that possess aromatase–STS inhibitory properties. The further development of potent STS inhibitors will allow their potential therapeutic value to be explored in a variety of hormone-dependent cancers and possibly other non-oncological conditions.

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The Unusual Role of Pro in Cu(II) Binding by His2-Cyclopentapeptide

International Journal of Molecular Sciences ◽

10.3390/ijms22126628 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6628

Author(s):

Aleksandra Pieniężna ◽

Aleksandra Kotynia ◽

Justyna Brasuń

Keyword(s):

Amino Acid ◽

Potentiometric Titration ◽

Amino Acid Residue ◽

Strong Impact ◽

Mononuclear Complexes ◽

Study Results ◽

Metal Ratio ◽

Ph Range ◽

L1 And L2

In this paper, we present findings from studying the interaction of copper(II) ions with the His2-cyclopentapeptide and the role of proline used for the purpose of potentiometric titration and UV-Vis, CD and EPR spectroscopic measurements. Experiments of two homodetic peptides differing by one amino acid residue were conducted for a ligand to metal ratio of 1:1 in the pH range 2.5–11.0. The presented studies reveal that peptides form only mononuclear complexes, and the CuH2L complex appears in the system first (for both L1 and L2). Study results show that the presence of Pro influences the structure of formed complexes and their stabilities and has a strong impact on the efficiency of copper(II) coordination.

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Regulation of the synthesis and hydrolysis of ATP by mitochondrial ATPase. Role of Mg2+.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)43969-x ◽

1983 ◽

Vol 258 (22) ◽

pp. 13673-13679 ◽

Cited By ~ 1

Author(s):

A Gómez-Puyou ◽

G Ayala ◽

U Muller ◽

M Tuena de Gómez-Puyou

Keyword(s):

Mitochondrial Atpase ◽

Hydrolysis Of

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The role of pretreatment in improving the enzymatic hydrolysis of lignocellulosic materials

Bioresource Technology ◽

10.1016/j.biortech.2015.08.061 ◽

2016 ◽

Vol 199 ◽

pp. 49-58 ◽

Cited By ~ 348

Author(s):

Shaoni Sun ◽

Shaolong Sun ◽

Xuefei Cao ◽

Runcang Sun

Keyword(s):

Enzymatic Hydrolysis ◽

Lignocellulosic Materials ◽

Hydrolysis Of

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“Newton’s cradle” proton relay with amide–imidic acid tautomerization in inverting cellulase visualized by neutron crystallography

Science Advances ◽

10.1126/sciadv.1500263 ◽

2015 ◽

Vol 1 (7) ◽

pp. e1500263 ◽

Cited By ~ 53

Author(s):

Akihiko Nakamura ◽

Takuya Ishida ◽

Katsuhiro Kusaka ◽

Taro Yamada ◽

Shinya Fushinobu ◽

...

Keyword(s):

Glycoside Hydrolases ◽

Side Chain ◽

Enzymatic Reactions ◽

X Ray Diffraction ◽

Peptide Bonds ◽

Proton Relay ◽

Newton’S Cradle ◽

Dynamics Simulations ◽

Hydrolysis Of

Hydrolysis of carbohydrates is a major bioreaction in nature, catalyzed by glycoside hydrolases (GHs). We used neutron diffraction and high-resolution x-ray diffraction analyses to investigate the hydrogen bond network in inverting cellulase PcCel45A, which is an endoglucanase belonging to subfamily C of GH family 45, isolated from the basidiomycete Phanerochaete chrysosporium. Examination of the enzyme and enzyme-ligand structures indicates a key role of multiple tautomerizations of asparagine residues and peptide bonds, which are finally connected to the other catalytic residue via typical side-chain hydrogen bonds, in forming the “Newton’s cradle”–like proton relay pathway of the catalytic cycle. Amide–imidic acid tautomerization of asparagine has not been taken into account in recent molecular dynamics simulations of not only cellulases but also general enzyme catalysis, and it may be necessary to reconsider our interpretation of many enzymatic reactions.

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The role of cellulase concentration in determining the degree of synergism in the hydrolysis of microcrystalline cellulose

Biochemical Journal ◽

10.1042/bj2550895 ◽

1988 ◽

Vol 255 (3) ◽

pp. 895-899 ◽

Cited By ~ 73

Author(s):

J Woodward ◽

M Lima ◽

N E Lee

Keyword(s):

Microcrystalline Cellulose ◽

Apparent Relationship ◽

Beta Glucosidase ◽

Hydrolysis Of

Microcrystalline cellulose (10 mg of Avicel/ml) was hydrolysed to glucose by different concentrations of the purified cellulase components endoglucanase (EG) II and cellobiohydrolases (CBH) I and II, alone and in combination with each other, in the presence of excess beta-glucosidase. At a concentration of 360 micrograms/ml (160 micrograms of EG II/ml, 100 micrograms of CBH I/ml and 100 micrograms of CBH II/ml) the degree of synergism among them was negligible. As the concentration of cellulase decreased, the degree of synergism increased, reaching an optimum at 20 micrograms/ml (5 micrograms of EG II/ml, 10 micrograms of CBH I/ml and 5 micrograms of CBH II/ml). There was no apparent relationship between the ratio of the components and the degree of synergism. The latter is probably due, though it could not be proved, to the level of saturation of the substrate with each component. Inhibition of Avicel hydrolysis was observed when the substrate was incubated with saturating and nonsaturating concentrations of a mixture of EG II and CBH I respectively. A similar result was also observed with a combination of EG I and EG II.

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Chemistry of oxylipin pathways in marine diatoms

Pure and Applied Chemistry ◽

10.1351/pac200779040481 ◽

2007 ◽

Vol 79 (4) ◽

pp. 481-490 ◽

Cited By ~ 80

Author(s):

Angelo Fontana ◽

Giuliana d'Ippolito ◽

Adele Cutignano ◽

Antonio Miralto ◽

Adrianna Ianora ◽

...

Keyword(s):

Higher Plants ◽

Larval Growth ◽

Marine Macroalgae ◽

High Concentration ◽

Marine Diatoms ◽

Fatty Acid Derivatives ◽

The Family ◽

Hydrolysis Of ◽

Catalyzed Oxidation

Oxylipins are important signal transduction molecules widely distributed in animals and plants where they regulate a variety of events associated with physiological and pathological processes. The family embraces several different metabolites that share a common origin from the oxygenase-catalyzed oxidation of polyunsaturated fatty acids. The biological role of these compounds has been especially studied in mammalians and higher plants, although a varied and very high concentration of these products has also been reported from marine macroalgae. This article gives a summary of our results concerning the oxylipin chemistry of marine diatoms, a major class of planktonic microalgae that discourage predation from their natural grazers, zooplanktonic copepods, using chemical warfare. These apparently harmless microscopic cells produce a plethora of oxylipins, including short-chain unsaturated aldehydes, hydroxyl-, keto-, and epoxyhydroxy fatty acid derivatives, that induce reproductive failure in copepods through abortions, congenital malformations, and reduced larval growth. The biochemical process involved in the production of these compounds shows a simple regulation based on decompartmentation and mixing of preexisting enzymes and requires hydrolysis of chloroplast-derived glycolipids to feed the downstream activities of C16 and C20 lipoxygenases.

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