Imidazole 5 -phosphate

V. 5-Amino-l-((3-D-ribofuranosyl)imidazole 5 -Phosphate, the Precursor of Pyramine in... 

From this observation of the inhibition by adenosine, and other observations, Newell and Tucker suspected the existence of a common synthetic pathway for adenosine and thiamine, and proved (with the help of a collection of mutants) that the bifurcation occurred after the 5-amino- l-(P-D-ribofura-nosyl)imidazole 5 -phosphate (46) step (Scheme 23). Finally, they found that 5-amino-l-(0-D-ribofuranosyl)imidazole (47), labeled with l4C in the imidazole ring, was incorporated into pyramine without significant loss of molar radioactivity by a mutant that is able to use this nucleoside (presumably after phosphorylation).53,54... 

Amino acid ester side groups are not the only units that sensitize the system to hydrolysis. The imidazolyl group has an even greater effect.197-198-219 For example, polymer 3.86, prepared by the reaction of poly(dichlorophosphazene) with imidazole, is so unstable hydrolytically that it decomposes in moist air to imidazole, phosphate, and ammonia. This is too high a sensitivity for most biomedical applications. Hence, an emphasis has been placed on the study of polymers such as 3.87 in which a hydrophobic cosubstituent group, such as aryloxy, is present to reduce the rate of erosion. 

Another class of fixatives used significantly in the past is mercuric-chloride fixatives. These do not initiate aldehyde linkages, but react with a number of amino acid residues such as thiols, amino groups, imidazole, phosphate and hydroxyl groups. On the positive side, fixation times are short, in the order of five to eight hours. On the negative side, it should be noted that mercuric chloride is highly toxic,... 

General base catalysis by formate, acetate, imidazole, phosphate, and methoxyamine is also observed in the hydrolysis of ethyl trifluorothiol-acetate the Bronsted exponent j8 is 0 33. In acetate buffers a careful kinetic study demonstrated inhibition by acetic acid. Therefore, the acetate reaction also involves a tetrahedral intermediate according to scheme C. No complex formation of the substrate with acetic acid, which could alternatively cause inhibition, could be found. Scheme C accounts for the acetate catalysis and inhibition by acetic acid. In scheme C, a general base mechanism is written, the same mechanism which unequivocally applies to the water reaction. 

The tribological properties of three novel anions ILs were studied. Phosphate ILs were synthesized and evaluated as lubricants for steel/steel sliding pairs [91,92]. It was found that alkyl imidazole phosphate ILs exhibit excellent lubrication and anticorrosion properties (Fig. 9.16). This was attributed to their reaction with the friction surface to generate a FePO -alkyl imidazole protective film which can significantly reduce friction and wear. 

Zhang L, Feng DP, Xu B et al (2009) The friction and wear characteristics and lubrication mechanism of imidazole phosphate ionic liquid. Sci China Ser E-Tech Sci 52 1191-1194... 

Polymer XII (and model oligomers based on the same repeating structure) hydrolyze to ethanol, amino acid, phosphate and ammonia. Species of type XII hydrolyze to imidazole, phosphate and ammonia. The utility of this mechanism for polymers such as those shown in Scheme II is obvious. 

Silversmith, R.E., Appleby, J.L. and Bourret, R.B. (1997). Catalytic mechanism of phosphorylation and dephosphorylation of CheY kinetic characterization of imidazole phosphates as phosphodonors and the role of add catalysis. Biochemistry 36, 14965-14974. 

Because sugars are involved in most of the mechanisms established for the synthesis of these heterocycles, the development of carbohydrate chemistry has been most helpful in these researches—especially for the preparation of specifically labeled molecules. Conversely, the contribution of these efforts to carbohydrate chemistry and biochemistry has shown the involvement in biosynthesis of 1 -deoxy-D-f/rreo-pentulose—scarcely before recognized and considered a rare sugar—and of fully functionalized pentuloses of still unknown configuration (or their phosphates). Finally, evidence has been found in prokaryotes for a most extraordinary transformation of 5-amino-l-(P-D-ribofuranosyl)imidazole 5 -phos-phate into a pyrimidine. Surely, this transformation should be explained in terms... 

Phosphazene polymers can act as biomaterials in several different ways [401, 402,407]. What is important in the consideration of skeletal properties is that the -P=N- backbone can be considered as an extremely stable substrate when fluorinated alcohols [399,457] or phenoxy [172] substituents are used in the substitution process of the chlorine atoms of (NPCl2)n> but it becomes highly hydrolytically unstable when simple amino acid [464] or imidazole [405-407] derivatives are attached to the phosphorus. In this case, an extraordinary demolition reaction of the polymer chain takes place under mild hydrolytic conditions transforming skeletal nitrogen and phosphorus into ammonium salts and phosphates, respectively [405-407,464]. This opens wide perspectives in biomedical sciences for the utilization of these materials, for instance, as drug delivery systems [213,401,405,406,464] and bioerodible substrates [403,404]. 

The dialkyl(l-methylacetonyl)phosphates, which were easily hydrolyzed, are obtained in higher than 90% yields. Such reactions can also be carried out by making the phosphoric imidazolide in situ from the di(l,2-dimethylethylene)pyrophosphate and imidazole.[10]... 

Biosorption is a rather complex process affected by several factors that include different binding mechanisms (Figure 10.4). Most of the functional groups responsible for metal binding are found in cell walls and include carboxyl, hydroxyl, sulfate, sulfhydryl, phosphate, amino, amide, imine, and imidazol moieties.4 90 The cell wall of plant biomass has proteins, lipids, carbohydrate polymers (cellulose, xylane, mannan, etc.), and inorganic ions of Ca(II), Mg(II), and so on. The carboxylic and phosphate groups in the cell wall are the main acidic functional groups that affect directly the adsorption capacity of the biomass.101... 

Di-t-butyl phosphate complexes of zinc were synthesized as precursors for ceramic material formation. A tetrameric zinc complex was characterized from the treatment of zinc acetate with the phosphate resulting in a compound with a bridging oxo at the center, [Zn4(/i4-0)(di-t-butyl phosphate)6]. In the presence of auxiliary donor ligands such as imidazole or ethylenediamine, monomeric complexes are formed, [Zn(di-t-butyl phosphate)2(imidazole)4]. It is also possible to convert the tetramer into the monomer by treating with a large excess of imidazole.41... 

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