Proteins and polyphosphates

From the experiments it is clear that poly electrolyte is adsorbed on the surface of the black lipid film. This applies both to the experiments with gelatin and bovine serum albumin, which gave no decrease of film resistance, and to the experiments with bovine erythrocyte ghost protein and polyphosphate. The adsorption of protein on the phospholipid-water interface may be controlled independently by investigating the electrophoretic behavior of emulsion droplets, stabilized by phospholipid, in a protein solution, as a function of pH. In this way Haydon (3) established protein adsorption on the phospholipid-water interface. If the high resistance (107 ohms per sq. cm.) of black lipid films is to be ascribed to the continuous layer of hydrocarbon chains in the interior of the film, as is generally done, an increase in film conductivity is not expected from adsorption without penetration. 

V p=oas of the phosphodiester backbone of nucleic acid (DNA and RNA) May also be due to the presence of phosphorylated proteins and polyphosphate storage products... 

The eytoplasm is a viscous fluid and contains within it systems of paramount importance. These are the nucleus, responsible for the genehc make-up of the cell, and the ribosomes, whieh are the site of protein synthesis, hi addihon are found granules of reserve material suehas polylydioxybutyric add, an energy reserve, and polyphosphate or volutin granules, the exact funchon of which has not yet been elucidated. The prokaiyohc nueleus or bacterial chromosome exists in the cytoplasm in the form of a loop and is not surrounded by a nuclear membrane. Bacteria cany other chromosomal elements episomes, which are portions of the main chromosome that have become isolated firm it, and plasmids, whieh may be called miniature chromosomes. These are small annular pieees of DNA whieh carry a limited amount of genetic information. 

On the other hand, Widra found metachromatic granules to contain protein-bound lipide, RNA, and polyphosphates. 

Fig. 13. Photoaffinity probes for studying transcription factors, inositol-polyphosphate binding proteins, and biopolymers containing an SH2 domain...

Because many cells maintain ATP, ADP, and AMP concentrations at or near the mass action ratio of the adenylate kinase reaction, the cellular content of this enzyme is often quite high. A consequence of such abundance is that, even after extensive purification, many proteins and enzymes contain traces of adenylate kinase activity. The presence of this kinase can confound the quantitative analysis of processes that either require ADP or are carried out in the presence of both ATP and AMP. Furthermore, the equilibrium of any reaction producing ADP may be altered if adenylate kinase activity is present. To minimize the effect of adenylate kinase, one can utilize the bisubstrate geometrical analogues Ap4A and ApsA to occupy simultaneously both substrate binding pockets of this kinase . Typical inhibitory concentrations are 0.4 and 0.2 mM, respectively. Of course, as is the case for the use of any inhibitor, one must always determine whether Ap4A or ApsA has a direct effect on a particular reaction under examination. For example. Powers et al studied the effect of a series of o ,co-di-(adenosine 5 )-polyphosphates (e.g., ApnA, where n =... 

N. A. Robinson, N. H. Goss and H. G.Wood (1984). Polyphosphate kinase from Propionibaterium shermanii-. formation of an enzymatically active soluble complex with basic proteins and characterization of synthesed polyphosphate. Biochem. Int., 8, 757-769. 

The first published use of cryoprotectants for muscle proteins, found to be successful in commercial application, was a combination of sucrose (10%) and polyphosphate (0.2-0.5%) which... 

Enzymatic activity, however, is not merely associated with covalent structures, but chiefly with tertiary structure which is still more difficult to determine. The crucial role of tertiary structure is proved by the fact that denaturation brings about inactivation. Even with proteins which may be reversibly denatured, such as chymotrypsin and trypsin, activity is lost as long as denaturation persists. Ribonuclease appeared for a while to be an exception, since it was still active in 8 M urea. But it was shown later that phosphate ions, at a concentration as low as 0.003 M, and polyphosphates induced in urea-denatured ribonuclease spectral changes usually associated with refolding (164). It could then be assumed that ribonucleic acid, the actual substrate, was also able to refold the denatured form and prevent inactivation in this way. In other words, even in ribonuclease, the active center is probably not built by adjacent residues in a tail or a ring, but by some residues correctly located in space by the superimposed... 

Principles of restructuring meats were reviewed by Pearson and Dutson (1987). Basically, red or poultry meats are flaked or chunked into small pieces, mixed or tumbled with salt and polyphosphates to extract heat-coagulable protein, shaped into loaf pans... 

CE has also been successfully apphed to the study of muscle proteins, and some of these applications have been recently reviewed. - - Methods for the determination of muscle proteins were based on CZE, SDS-CE, or isoelectric focusing (CEIF). Meat species identification was carried out by analyzing sarcoplasmic or myofibrillar proteins by a replaceable polymer-filled SDS-CE method (Table 30.8). However, the analysis of sarcoplasmic protein profiles allowed better differentiation among beef, pork, and turkey meat (Figure 30.8). The importance of sample preparation in the established method was highlighted since sarcoplasmic proteins extracted by simply homogenizing meat with cold bidistilled water were most useful for meat species identification when protein profiles were examined by linear discriminant analysis. On the other hand, myofibrillar proteins extracted with 0.6 M NaCl/0.01 M phosphate buffer with 0.5% polyphosphates (pH 6.0) were not useful for raw meat species identification, although they may be of importance in the identification of heat-processed meats. ... 

In addition to prokaryotic PHA accumulation, low-molecular mass poly-hydroxybutyrate complexed to other macromolecular cell components like proteins or polyphosphates (cPHB) can be found in the tissue of eukaryotic organisms. cPHB classically occurs in low quantities in the organisms and does not serve as storage material not all of the details of its metabolic functions have been elucidated [9]. 

Not compatible with anionic compounds, proteins, zinc salts and polyphosphates... 

The addition of phosphates (polyphosphates) to food affects the hydration of proteins and polysaccharides and their colloidal properties. It is used to increase the water-holding capacity (WHC) capacity, sometimes referred to as water-binding capacity (WBC) when water is added to cured meat and certain meat products. Phosphates also provide the appropriate texture to processed cheeses made from traditional cheese and emulsifying salts, often with the... 

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