Hydrolysis of the Alkyl-Phosphate Bond in Certain Dialkyl Aryl Phosphorothioate Insecticides by Rats, Cockroaches, and Alkali1

1958 ◽  
Vol 51 (6) ◽  
pp. 800-803 ◽  
Author(s):  
F. W. Plapp ◽  
J. E. Casida
Keyword(s):  
Phosphate Bond ◽  
Alkyl Phosphate ◽  
Hydrolysis Of

Cleavage of the phosphate bond in the hydrolysis of nucleotidyl (5′ → N) - amino acids

1967 ◽  
Vol 3 (2) ◽  
pp. 101-104 ◽  
Author(s):  
E. P. Savel'ev ◽  
N. N. Preobrazhenskaya ◽  
Z. A. Shabarova ◽  
M. A. Prokof'ev
Keyword(s):  
Amino Acids ◽  
Phosphate Bond ◽  
Hydrolysis Of

scholarly journals Hydrolysis of polynucleotides and the characterization of their secondary structure. A theoretical study

1968 ◽  
Vol 106 (3) ◽  
pp. 725-731 ◽  
Author(s):  
R A Cox
Keyword(s):  
Secondary Structure ◽  
Theoretical Study ◽  
Linear Polymers ◽  
Hairpin Loop ◽  
Base Pairs ◽  
Phosphate Bond ◽  
Hairpin Loops ◽  
Hydrolysis Of

1. Single-stranded RNA may be regarded as an assembly of L hairpin loops each stabilized by N base pairs and each containing b unpaired residues; one loop is connected to another by c residues. 2. A theory based on the statistics of the random degradation of linear polymers was developed to relate N, b and c with the probability, p, of hydrolysing a diesterified phosphate bond. 3. The number of residues per hairpin loop, which is 2N+b, is related to the fraction, f, of the original loops remaining intact by the equation: 2N+b=logf/log(1–p). 4. The theory was extended to show that the number of residues per loop may be evaluated by fractionating the RNA after hydrolysis and examining the secondary structure of each fraction. Fragments that are shorter than the hairpin loop cannot reproduce the original secondary structure. The probability that a fragment will form an intact loop increases most rapidly for fragments of between 2N+b and 2(2N+b)+c residues. 5. The probability of producing a fragment capable of forming one, and only one, hairpin loop was related to N, b and c.

scholarly journals A calcium ion-dependent adenosine triphosphate pyrophosphohydrolase in plasma membrane from rat liver. Demonstration that the adenosine triphosphate analogues adenosine 5′-[βγ-imido]triphosphate and adenosine 5′-[βγ-methylene]-triphosphate are substrates for the enzyme

1978 ◽  
Vol 171 (3) ◽  
pp. 817-820 ◽  
Author(s):  
H Flodgaard ◽  
C Torp-Pedersen
Keyword(s):  
Plasma Membrane ◽  
Adenosine Triphosphate ◽  
Rat Liver ◽  
Specific Activity ◽  
Fold Increase ◽  
Sucrose Density Gradient ◽  
Partial Purification ◽  
Phosphate Bond ◽  
Hydrolysis Of ◽  
Fold Activation

An ATP pyrophosphohydrolase in a rat liver plasma-membrane subfraction was studied with respect to specific Ca2+ activation of the beta-phosphate bond hydrolysis. ATP and, in addition, adenosine 5′-[betagamma-imido]triphosphate and adenosine 5′-[betagamma-methlylene]triphosphate were substrates for Ca2+-stimulated enzymic hydrolysis of the beta-phosphate bond. A 15-fold activation was observed by raising the free Ca2+ concentration from 10(-7) to 10(-5) M. Mg2+ had little effect. Solubilization in 1% deoxycholate and partial purification on a sucrose density gradient resulted in a 5-fold increase in specific activity with unaltered Ca2+-stimulation pattern. The possible importance of the enzyme in Ca2+ transport is discussed.

Synthesis of Mesoporous Titanium Phosphate

2000 ◽  
Vol 628 ◽  
Author(s):  
C.J. Barbé ◽  
D.R.G. Mitchell ◽  
E. Drabarek ◽  
J.R Bartlett ◽  
J.L. Woolfrey ◽  
...  
Keyword(s):  
Significant Proportion ◽  
Titanium Isopropoxide ◽  
Processing Parameters ◽  
Basic Solution ◽  
High Porosity ◽  
Subsequent Aging ◽  
Alkyl Phosphate ◽  
Acidic Conditions ◽  
Hydrolysis Of ◽  
Long Chain

ABSTRACTMesoporous titanium phosphates were synthesised using three different approaches, involving reactions of titanium isopropoxide with long-chain alkyl phosphates, and subsequent aging at 80°C for several days. The resulting powders were characterised using XRD, TEM and N2 sorption.The first approach involved the classical MCM methodology, where the modified titanium precursor was added to an alkylphosphate micellar solution. The resulting solids possess an organised, lamellar mesostructure. However, removal of the surfactant, either by heating or leaching in strong basic solution, leads to the collapse of the lamellar mesostructure.In the second route, titanium alkoxide was pre-reacted with the long-chain alkyl phosphate, then hydrolysed with a large excess of water prior to ageing. Although the structure of the as-precipitated samples could be easily tailored by changing the processing parameters such as the alkyl phosphate chain length or phosphate/titanium ratio, surfactant removal by heating invariably led to the production of microporous samples.The third approach involved the hydrolysis of the acetylacetone-modified titanium isopropoxide with excess water. The alkyl phosphate was then introduced into the resulting suspension. Subsequent ageing under acidic conditions destabilised the particles, leading to aggregation and subsequent gelation. In contrast to the previous approaches, the pyrolysed solid contained a significant proportion of mesopores, a high porosity (40%) and a surface area exceeding 300 m2.g-1.

Fine Structural Localization of Acyltransferases Involved in Lipid Synthesis in Intestinal Mucosa.

1970 ◽  
Vol 28 ◽  
pp. 54-55
Author(s):  
R. J. Barrnett ◽  
J. A. Higgins
Keyword(s):  
Smooth Endoplasmic Reticulum ◽  
Lipid Synthesis ◽  
Mucosal Cell ◽  
Structural Localization ◽  
Morphological Studies ◽  
Mucosal Cells ◽  
Initial Appearance ◽  
Sh Group ◽  
Hydrolysis Of ◽  
Intestinal Mucosal Cells

The main products of intestinal hydrolysis of dietary triglycerides are free fatty acids and monoglycerides. These form micelles from which the lipids are absorbed across the mucosal cell brush border. Biochemical studies have indicated that intestinal mucosal cells possess a triglyceride synthesising system, which uses monoglyceride directly as an acylacceptor as well as the system found in other tissues in which alphaglycerophosphate is the acylacceptor. The former pathway is used preferentially for the resynthesis of triglyceride from absorbed lipid, while the latter is used mainly for phospholipid synthesis. Both lipids are incorporated into chylomicrons. Morphological studies have shown that during fat absorption there is an initial appearance of fat droplets within the cisternae of the smooth endoplasmic reticulum and that these subsequently accumulate in the golgi elements from which they are released at the lateral borders of the cell as chylomicrons.We have recently developed several methods for the fine structural localization of acyltransferases dependent on the precipitation, in an electron dense form, of CoA released during the transfer of the acyl group to an acceptor, and have now applied these methods to a study of the fine structural localization of the enzymes involved in chylomicron lipid biosynthesis. These methods are based on the reduction of ferricyanide ions by the free SH group of CoA.

Lattice imaging and pore structure of β ferric oxyhydroxide

1978 ◽  
Vol 36 (1) ◽  
pp. 264-265
Author(s):  
T. Baird ◽  
J.R. Fryer ◽  
S.T. Galbraith
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Bulk Material ◽  
Model Structure ◽  
Bulk Crystals ◽  
Lattice Imaging ◽  
Thin Sections ◽  
Ferric Oxyhydroxide ◽  
Resolution Electron ◽  
Hydrolysis Of

Introduction Previously we had suggested (l) that the striations observed in the pod shaped crystals of β FeOOH were an artefact of imaging in the electron microscope. Contrary to this adsorption measurements on bulk material had indicated the presence of some porosity and Gallagher (2) had proposed a model structure - based on the hollandite structure - showing the hollandite rods forming the sides of 30Å pores running the length of the crystal. Low resolution electron microscopy by Watson (3) on sectioned crystals embedded in methylmethacrylate had tended to support the existence of such pores.We have applied modern high resolution techniques to the bulk crystals and thin sections of them without confirming these earlier postulatesExperimental β FeOOH was prepared by room temperature hydrolysis of 0.01M solutions of FeCl3.6H2O, The precipitate was washed, dried in air, and embedded in Scandiplast resin. The sections were out on an LKB III Ultramicrotome to a thickness of about 500Å.

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