Phosphorylation properties

Nuclear oxidative phosphorylation is difficult to quantify. Although oxygen uptake in the nucleus can be measured, no exact P/O ratio is available. This is because only the AMP already present in the nuclear preparation can be converted to ATP any AMP added to the nuclei remains unaltered. An intriguing observation is the effect of DNase on the phosphorylation of AMP. (Allfrey has proposed that DNase blocks ATP synthesis in the nucleus indirectly namely, by inhibition of the nuclei by the histones, which after DNA extraction are no longer associated with DNA by salt linkages [35].) The enzymic extraction of 55% of the DNA in the nucleus leads to the loss of nuclear phosphorylation properties, which can be restored by adding DNA to the system. The effect of DNA is not specific because DNA can be replaced by RNA, polyadenylic acid, heparin, chondroitin sulfate, and polyethylene sulfate. Oxidative phosphorylation in thymus nuclear preparation has been confirmed in two laboratories. Whole body doses of ionizing radiation inhibited oxidative phosphorylation in thymus nuclei. 

Whole cells cannot be removed from the nuclear pellet by ordinary tissue fractionation procedures, and only by differential centrifugation in a 2.20 m sucrose solution can the normal nuclei and the intact cells be separated. Unfortunately, such a technique destroys both the nuclear phosphorylating properties and the nuclear capacity to take up radioactive amino acids or orotic acid. 

The purity and integrity of Arahidopsis mitochondria was found to be about 90% based on galactolipid analysis and chlorophyll content (data not shown) and electron microscopy (Fig. 2). In addition, purified mitochondria exhibit good oxidative and phosphorylative properties as indicated by the high values of oxidation rates, respiration control and membrane potential (data not shown). 

Phosphorylated cottons are flame resistant ia the form of the free acid or the ammonium salt. Siace these fabrics have ion-exchange properties, conversion to the sodium salt takes place readily during laundering if basic tap water is used. However, flame resistance can be restored if the fabric is treated with either acetic acid [1563-80-8] or ammonium hydroxide [1336-21 -6] after washing. 

The unique properties and actions of an inhibitory substance can often help to identify aspects of an enzyme mechanism. Many details of electron transport and oxidative phosphorylation mechanisms have been gained from studying the effects of particular inhibitors. Figure 21.29 presents the structures of some electron transport and oxidative phosphorylation inhibitors. The sites of inhibition by these agents are indicated in Figure 21.30. 

The thylakoid membrane is asymmetrically organized, or sided, like the mitochondrial membrane. It also shares the property of being a barrier to the passive diffusion of H ions. Photosynthetic electron transport thus establishes an electrochemical gradient, or proton-motive force, across the thylakoid membrane with the interior, or lumen, side accumulating H ions relative to the stroma of the chloroplast. Like oxidative phosphorylation, the mechanism of photophosphorylation is chemiosmotic. 

Most of the phosphoryl and thiophosphoryl compounds are colourless gases or volatile liquids though PSBt3 forms yellow crystals, mp 37.8°, POI3 is dark violet, mp 53°, and PSI3 is red-brown, mp 48°. All are monomeric tetrahedral (C y) or pseudotetrahedral. Some physical properties are in Table 12.4. The P-O interatomic... 

A condition in which a receptor is unresponsive despite the presence of agonist also referred to as a refractory state . Typically this state is the consequence of prolonged exposure to agonist, and occurs after receptor activation it is a built in mechanism to limit a receptor s effects. Mechanistically the desensitised state differs from the resting, closed state of a receptor because in the latter state, a receptor can respond to agonist. This difference predicts that these states are structurally distinct. The desensitised state may also be stabilised by very low concentrations of agonist, such that no measurable activation of the receptor precedes it. Desensitisation is an intrinsic property of many receptors but can also be influenced by other interactions or modifications, such as phosphorylation. 

Evolution has provided the cell with a repertoire of 20 amino acids to build proteins. The diversity of amino acid side chain properties is enormous, yet many additional functional groups have been selectively chosen to be covalently attached to side chains and this further increases the unique properties of proteins. Diese additional groups play a regulatory role allowing the cell to respond to changing cellular conditions and events. Known covalent modifications of proteins now include phosphorylation, methylation, acetylation, ubi-quitylation, hydroxylation, uridylylation and glycosyl-ation, among many others. Intense study in this field has shown the addition of a phosphate moiety to a protein... 

We have studied the extractant behavior of a series of compounds containing the carbamoylmethylphosphoryl (CMP) moiety in which the basicity of the phosphoryl group and the steric bulk of the substituent group are varied (10,LL). These studies have led to the development of extractants which have combinations of substituent groups that impart to the resultant molecule improved ability to extract Am(III) from nitric acid and to withstand hydrolytic degradation. At the same time good selectivity of actinides over most fission products and favorable solubility properties on actinide loading are maintained (11). 

The development of monoalkyl phosphate as a low-skin-irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste- and liquid-type skin cleansers, and also on phosphorylation reactions from the viewpoint of industrial production [26]. The preparation and industrial applications of phosphate esters as anionic surfactants were discussed [27]. 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

Yu, M., Goldberg, S., Goldberg, A.L. (1W2). Heat shock in Escherichia coli alters the protein-binding properties of the chaperonin groEL by inducing its phosphorylation. Nature 357, 167-169. 

Aldridge, W.N. and Street, B.W. (1964). Oxidative phosphorylation biochemical effects and properties of trialkyl tin. Biochemical Journal 91, 287-297. 

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