Phenol phosphorylation

Phenylphosphate synthase consists of three subunits with molecular masses of 70, 40, and 24kDa. Subunit 1 resembles the central part of classical phospho-enolpyruvate synthase which contains a conserved histidine residue. It catalyzes the exchange of free [ C] phenol and the phenol moiety of phenylphosphate but not the phosphorylation of phenol. Phosphorylation of phenol requires subunit 1, MgATP, and another protein, subunit 2 (40kDa), which resembles the N-terminal part of phosphoenolpyruvate synthase. Subunit 1 and 2 catalyze the following reaction ... 

CF = cardanol-formaldehyde resin (cured) MCPAF = monocar-danyl phosphoric acid-formaldehyde resin (cured) BrCF = bromo derivative of CF BrMCPAF = bromoderivative of MCPAF PF = phenol-formaldehyde (cured) MPPAF = monophenyl phosphoric acid-formaldehyde (cured), BrPF = bromo derivative of PF BrMPPAF = bromoderivative of MPPAF PPF = phenol-formaldehyde resin phosphorylated (cured). 

The phosphoryl group in phenylphosphate is derived from the -phosphate group of ATP. The free energy of ATP hydrolysis obviously favors the trapping of phenol K, 0.04 mM), even at a low ambient substrate concentration. The reaction is stimulated several fold by another protein, subunit 3 (24kDa). The molecular and catalytic features of phenylphosphate synthase resemble those of phosphoenolpyruvate synthase, albeit with interesting modifications. ... 

Narmandakh A, N Gad on, F Drepper, B Knapp, W Haehnel, G Fuchs (2006) Phosphorylation of phenol by phenylphosphate synthase role of histidine phosphate in catalysis. J Bacteriol 188 7815-7822. 

Allelopathic inhibition of mineral uptake results from alteration of cellular membrane functions in plant roots. Evidence that allelochemicals alter mineral absorption comes from studies showing changes in mineral concentration in plants that were grown in association with other plants, with debris from other plants, with leachates from other plants, or with specific allelochemicals. More conclusive experiments have shown that specific allelochemicals (phenolic acids and flavonoids) inhibit mineral absorption by excised plant roots. The physiological mechanism of action of these allelochemicals involves the disruption of normal membrane functions in plant cells. These allelochemicals can depolarize the electrical potential difference across membranes, a primary driving force for active absorption of mineral ions. Allelochemicals can also decrease the ATP content of cells by inhibiting electron transport and oxidative phosphorylation, which are two functions of mitochondrial membranes. In addition, allelochemicals can alter the permeability of membranes to mineral ions. Thus, lipophilic allelochemicals can alter mineral absorption by several mechanisms as the chemicals partition into or move through cellular membranes. Which mechanism predominates may depend upon the particular allelochemical, its concentration, and environmental conditions (especially pH). 

Combined dipole moment and Kerr effect studies are regularly used by Russian workers for the conformational analysis of phosphorus heterocyc1es.135 230 In a study of the interaction of phenol with phosphoryl groups the Kerr effect was used to evaluate not only the extent of hydrogen bonding but also the influence of changes in polarity and polarisation upon stability constants.231 In a similar study the orientation of the aryl groups of 1,3,5-triazaphosphorines (82) were shown to be less coplanar than biphenyl in the gas phase. 2 3 2... 

Noting that the reaction of cycloheptaamylose with diphenyl pyrophosphate produces equal amounts of phenol, monophenyl phosphate, and phosphorylated cycloheptaamylose, Hennrich and Cramer (1965) proposed a nucleophilic mechanism (Scheme IV). According to this mechanism, a rapid, reversible association of the pyrophosphate with cycloheptaamylose... 

The phosphoramidic chloride (11) has been employed to phosphorylate phenols and alcohols, including carbohydrates.16 Other activity in phosphorylation chemistry has been mostly concentrated in two main areas. In the first of these, Japanese workers have continued their studies on the use of 2-substituted-4-nitrophenyl-phosphoric acids. The 7V-protonated form of the 2-dimethylamino-compound (12 R = Me) is a better phosphorylating agent than the corresponding 2-diethylamino-compound. The reaction of (12) with hydroxy-amines results in selective O-phos-... 

Phosphorylation of phenolate anions with dimethyl phosphorochloridothionate in water-dichloromethane systems normally gives large amounts of dithiopyrophos-phate because of extensive hydrolysis of the phosphorus chloride, but in the presence of tetrabutylammonium salts and 1 % imidazole, phosphorylation of the phenolate anion is complete. The explanation lies in an evident combination of activation of acylating agent (by imidazole) and of nucleophile (by phase-transfer catalysis).71... 

The rate of reaction of phosphorus oxychloride with phenols to produce triaryl phosphates is increased by the addition of quaternary ammonium salts and the reaction temperature can be reduced without loss of overall yield [1,2]. The analogous reaction between phenoxide anions and thiophosphoryl chloride produces aryl phosphoro-dichloridothoates [3]. As with the acylation of enolizable (3-dicarbonyl compounds (3.3.12), phosphorylation leads to the predominant formation of the E-O-phos-phoryiated derivatives [4,5]. 

The catalysed two-phase adaptation of the Atherton-Todd procedure is effective for the phosphorylation of primary alcohols and of phenols [6] to produce trialkyl phosphates and dialkyl aryl phosphates. Trialkyl phosphates have also be obtained in high yield (>75%) from the alkylation of preformed tctra-n-butylammonium di-/-butylphosphate [7], Subsequent cleavage of the /-butyl groups provide a simple synthesis of monoalkyl phosphates. 

Atherton-Todd phosphorylation of alcohols and phenols (Table 3.22)... 

Diethyl phosphate esters of the sterically congested phenols of calixarenes have been prepared in acceptable yields (>55%) and used in the preparation of meta-cyclophanes [8]. The corresponding reaction using diethyl phosphite, with triethylamine in place of the quaternary ammonium catalyst, results in only partial phosphorylation of the hydroxyl groups. 

These compounds contain the fragment R as an alkyl or aryl moiety. In other words, they result from the esterification of an alcohol or a phenol with nitrous acid, nitric acid, phosphoric acid, sulfuric acid, or sulfamic acid, respectively. Many of the esters to be examined in this chapter must be activated prior to eliciting their effects, e.g., the organic nitrites and nitrates, which act as donors of nitric oxide or an analogous molecule, and phosphates, which are activated by hydrolysis or even by phosphorylation (antiviral agents). Sulfates are very seldom active or used as prodrugs, but they have significance as metabolites and as industrial xenobiotics. 

Table II. Uncoupling of Oxidative Phosphorylation by Phenols at pH 7.5 and Physicochemical Constants Used ...

The objectives of the studies reported herein were to (a) compare the effects of a series of phenolic acids, coumarins, and flavonoids on whole chain electron transport and phosphorylation in Isolated plant chloroplasts and mitochondria and (b) identify specific sites of inhibition with polarographic and enzymatic techniques. Exploratory studies were conducted with the 20 compounds listed in Table I. The three glycosides are shown indented below the corresponding aglycones. Detailed studies were conducted with the six compounds, one representative member from each chemical family, designated with an asterisk. 

Regardless of the source, phenolic acids are ultimately broken down to gaseous products such as CO2 and methane. This breakdown occurs by three general methods (i) aerobic respiration, using molecular oxygen as an electron acceptor, the end product being CO2, (ii) anaerobic respiration with electron acceptors such as nitrate and (iii) anaerobic fermentation with phosphorylation reactions involving no external electron acceptor (50). 

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