Polyphosphates high molecular

Propionibacteria contain large amounts of polyphosphates. High-molecular-weight (acid-insoluble) compounds containing from 70 to 500 residues of... 

Many compositions involve environmentally dangerous products, such as chromates, fatty amines of high molecular weights, imidazolines, etc. The use of some of the alternatives, for instance, polyphosphate or polyphosphonate, is limited because they precipitate in the presence of the salts of alkaline earth metals or because of their high costs. 

Among condensed phosphate systems with polyvalent cations, the very complicated calcium salts have been much studied and a great number of compounds have been detected, often with several modifications (5, 27, 28, 34, 54, 79, 186, 137, 191, 198, 204, 211, 276, 805, 830). In this system special interest attaches to the occurrence of crystalline cross-linked phosphates (see Section V) and of calcium pentaphosphate, CayiPsOis (see Section IV,D,/). The end-product obtained by heating Ca(H2P04)2 in the free atmosphere is the high-molecular calcium polyphosphate, which crystallizes in several forms. The condensed strontium phosphates (246, 805) are similarly complicated and cannot readily be made the subject of a brief review. 

A comparative study of the products of dehydration of the dihydrogen monophosphates of polyvalent cations showed that the stable end-products for cations with ionic radii between 0.57 and 1.03 A. (Cu++, Mg++, Ni++, Co++, Fe++, Mn++, Zn"1-1", Cd++, A1+++) are tetrametaphosphates. When the cations are either larger or smaller the end-products of dehydration are crystalline high-molecular polyphosphates (Li+, Be++, K+, Rb+, Cs+, Ag+, Zn++, Cd++, Hg++, Ca++, Sr++, Ba++ Pb++, Cr+++, Fe+++, Bi+++). In the case of the alkali salts only sodium trimetaphosphate occurs as a condensed phosphate with a cyclic anion (304, 305). Up to the present, an alkali tctrametaphosphate has not been observed as the dehydration product of a dihydrogen monophosphate. Consequently, alkali tetrametaphosphates arc obtainable only indirectly. Reference is made later (Section IV,C,4) to the fact that the tetraphosphates of barium, lead, and bismuth are formed as crystalline phases from melts of the corresponding composition. There are also reports of various forms of several condensed phosphates of tervalent iron and aluminum (31, 242, 369). 

POa)xx-. Contrary to the old nomenclature (340), which is still often used, they should no longer be designated as metaphosphates. Such a change in nomenclature is all the more important since the high-molecular polyphosphates in question differ clearly from true metaphosphates in that solutions of true metaphosphates have a neutral reaction since they are salts of strong acids those of polyphosphates are weakly acidic on account of the free OH end groups. In this review the term metaphosphate will be used only for condensed phosphates with cyclic anions. 

High-molecular polyphosphates are practically stable in aqueous solution at room temperature and a pH near the neutral point. At 60°C the half-life is about 50 days but it decreases rapidly with rising temperature. The hydrolysis constant of the high-molecular phosphates at 60°C and pH 8 has the value K = 0.9 X 10 and is about a power of ten smaller than that of octaphosphate and roughly equal to that of hexaphosphate (see Fig. 7). 

Polyphosphates seem to pass through a minimum of stability for a chain length of about n = 10 359). Decreasing the pH accelerates hydrolysis. Thus, for example, the following values of tVi are found for high-molecular anions at 60°C with varying pH. Added cations have a similar action to... 

Numerous experimental and theoretical studies of problems in this field have appeared and these have been reviewed under the title Metal Com-plexing by Polyphosphates by van Wazer (342). The phenomena which have been mentioned may be considered in general as due to complex formation. However, a simple qualitative and quantitative description of the facts may also be obtained if solutions of high-molecular polyphosphates arc considered as micro-heterogeneous systems and if the bonding of polyvalent ions is interpreted as involving ion exchange phenomena on the polyphosphate chains (77, 313, 319, 324). 

A range of high-molecular alkali polyphosphates occur in several crystalline forms. In the case of the sodium and potassium compounds the trivial names Maddrell s and Kurrol s salts have been adopted and these... 

Table XVI summarizes both the crystallographic data for these high-molecular polyphosphates and also all data in the structures of other condensed phosphates from which unambiguous deductions can be made. It will be seen that two P—0 distances can be distinguished in all these compounds. One set of values represents the distance in the bridging P—-0—P bond. These lie between 1.56 and 1.68 A. The second group corresponds with bonds to isolated oxygen atoms and here the bond distance is appreciably...

In the system (KII2P04—H3P04) high-molecular potassium polyphosphates are formed on heating, together with acid mono- and di-phosphate but only a little oligophosphate (363). But tertiary P04 tetrahedra occur not only in phosphates with Na P < 1. They can also be detected in Graham s and Kurrol s salt with Mr P = 1 (224, 284, 85, 86) and are also formed in melts of anhydrous trimetaphosphates, especially in a dry atmosphere (364). Their equilibrium concentration in the melt is about 2%. 

In these, As04 tetrahedra are built into the polyphosphate chains (309). Since the P—0—As bond has much the same sensitivity to hydrolysis as the As—0—As bond, they are rapidly hydrolyzed in aqueous solution to monoarsenate and mixtures of polyphosphates, the mean chain length of which depends on the As P ratio in the starting material (74)- Contrary to an idea based originally on gravimetric analysis (309), the As atoms are not distributed regularly in the chain, but statistically (308). The observation that, after careful hydrolysis, the phosphate content is exclusively in the form of polyphosphates provides chemical proof of catenation in the poly-arsenatophosphate anions. When arsenatophosphates with more than five P atoms per atom of As are hydrolyzed by hot water trimetaphosphates are formed, just as they are formed for all other high-molecular polyphosphates in solution (316). 

There is a series of arsenatophosphates corresponding with each of the three forms of condensed potassium arsenate and phosphate, the transition points and melting point of which vary systematically with composition (see Fig. 10). A chain structure for the a-form of potassium arsenate and arsenophosphate may be inferred from their isomorphism with (KP03)xB. The 7-forms also contain high-molecular anionic chains for, when they are hydrolyzed, monoarsenate and polyphosphates with chain length up to n = 6 are formed, depending on their phosphorus content. No metaphosphate is produced, however. 

Miihlradt, P.R Synthesis of high molecular weight polyphosphate with a partially purified enzyme from Salmonella. J. Gen. Microbiol., 68, 115-122 (1971)... 

Figure 1.8 Illustration of the incomplete hydrolysis oflinear high-molecular-weight polyphosphates to cyclotriphosphate and orthophosphate (Thilo, 1956, 1962).

Figure 1.9 Results of a chromatographic examination of the hydrolysis products of Graham s salt at pH 4 and 90 °C (a) high-molecular-weight polyphosphates (b) cyclic phosphates containing four to six phosphorus atoms (c) cyclotriphosphate (d) pyrophosphate (e) tripolyphosphate (f) linear polyphosphates containing four to 15 phosphorus atoms (g) orthophosphate (Van Wazer, 1958).

PolyPs and PHB have been found to be associated with ion-conducting proteins such as the human erythrocyte Ca2+-ATPase pump (Reush et al, 1997) and the Streptomyces lividans potassium channel (Reusch, 1999b). Some enzymes of PolyP metabolism, such as polyphosphate glucokinase (Phillips et al, 1999) and yeast high-molecular-weight exopolyphosphatase (Andreeva et al, 2001, 2004), can contain tightly bound PolyP. 

Some authors doubt the possibility of a direct interrelation between PolyP and photosynthesis in algae (Rubtsov et al, 1977 Rubtsov and Kulaev, 1977). The following facts support this point of view. No high-molecular-weight PolyP was found in the chloroplasts of Acetabularia mediterranea (Rubtsov et al, 1977). The inhibitor analysis and detection of polyphosphate kinase activity in this alga (Rubtsov and Kulaev, 1977) point to the fact that PolyP is not directly, but rather indirectly, connected with the photosynthesis through the formation of ATP, which provides energy for P transport and PolyP synthesis. 

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