Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Water-protein NOEs

In the following, three different experiments are discussed, where short, high-power spin-lock pulses are used to purge the spectrum from undesired resonances. The experiments are (i) the HSQC experiment [5], (ii) experiments with C half-filter elements [6], and (iii) NOESY and ROESY experiments for the observation of water-protein NOEs [7]. In the first two experiments, spin-lock purge pulses are used to suppress the signals from... [Pg.151]

In agricultural applications, the most commonly analyzed constituents are water, protein, starch, sugars, and fiber [16-20]. Such physical or chemical functions such as hardness of wheat, minerals, and food values have no actual relation to chemicals seen in the NIR. These are usually done by inferential spectroscopy. That is, the effect of minerals or the relationship of the spectra to in vitro reactions is used in lieu of chemical analyses to NIR active constituents. Considering that all shipments of grain from the US since the 1980s have been cleared by NIR, it can be argued that this is a critical application of the technique. [Pg.178]

Less gas-liquid chromatographic interference occurs when protein in plasma and serum is precipitated with picric acid than with trichloroacetic acid or sulfosalicylic acid. Ultracentrifugation or membrane techniques could be used. The cation-exchange columns should be washed with water until no visible picric acid remains. [Pg.537]

Hydration of biopolymers is a mechanism for stabilizing these materials (Fig. 2.78). When proteins are conpletely dry, they tend to decompose. One way of evaluating hydration in polyions is to measure the dielectric constant of a solution containing a dissolved protein as a function of concentration at radio frequency. The dielectric constant falls with increase in concentration and the water per polyion can be calculated by assuming that water bound to the protein no longer makes any contribution to the dielectric constant. Thus, Buchanan calculated the irrotationally bound water from such expaiments. Some of this water is hidden in cavities within the structure of the protein molecule. [Pg.192]

Mossbauer spectroscopic measurements suggest that the hydration water of myoglobin and the internal motions of the protein are coupled. [ Fe]Ferricyanide diffused into the solvent of myoglobin crystals exhibits (x ) values equal to those for the heme iron for temperatures below 250 K, and greater than those for the heme iron at higher temperatures (50% greater at 300 K) (Parak, 1986). The [ Fe]ferricyanide in the crystal monitors motions of the hydration water [ Fe]ferricyanide in bulk water shows no Mossbauer spectrum. [Pg.88]

Figure 2.29. Detail of photosystem I, seen from the side, with the division between units A and B (see Fig. 2.27) in the middle. Chlorophyll molecules (chi) other than the six central ones involved in transfer of energy to the three Fe4S4 clusters (FeS) are omitted. Chlorophylls, phylloquinones (phy, also known as vitamin K) and iron-sulphur clusters are further indexed with the subimit label A, B or X (cf. Fig. 2.27), and the chlorophylls are shown with an index number 1 to 3. Other identified molecules include LHG (CggHygOjoP), LMG (C45H84OJQ) and a number of p-carotenes (BCR). The scattered dots are oxygen atoms of water molecules (no hydrogens are shown). Based on Protein Data Bank ID IJBO Jordan et ah, 2001). Figure 2.29. Detail of photosystem I, seen from the side, with the division between units A and B (see Fig. 2.27) in the middle. Chlorophyll molecules (chi) other than the six central ones involved in transfer of energy to the three Fe4S4 clusters (FeS) are omitted. Chlorophylls, phylloquinones (phy, also known as vitamin K) and iron-sulphur clusters are further indexed with the subimit label A, B or X (cf. Fig. 2.27), and the chlorophylls are shown with an index number 1 to 3. Other identified molecules include LHG (CggHygOjoP), LMG (C45H84OJQ) and a number of p-carotenes (BCR). The scattered dots are oxygen atoms of water molecules (no hydrogens are shown). Based on Protein Data Bank ID IJBO Jordan et ah, 2001).
It is noteworthy to point out that the preferential binding parameter provides an interconnection between the local and bulk properties in water+protein+cosolvent mixtures. Indeed, when the preferential binding parameter 1 23 is negative, a protein is preferentially hydrated (water is in excess), the protein is additionally stabilized and its solubility is decreased by the cosolvent. It seems that there is no exception to this rule. [Pg.280]

Supercritical extracts therefore have a unique and concentrated spectrum of lipophilic ingredients. They have the general advantage of being free of solvents, inorganic salts and heavy metals. They are practically sterile [10] and they need no preservatives since they do not provide a base for germ growth due to the absence of water, proteins and polysaccharides. All this allows a safe application and simple declaration. [Pg.62]

A 30 cm Protein Pak 300 SW column (Waters product no. 80013) and isocratic Waters HPLC were used to perform the chromatography studies. Solvent flow rate was fixed at 1.0 ml/min and 10 ml samples of 1-10 mg/ml were injected. Eluted components were detected by uv absorption at 280 nm. The retention times of myoglobin (18,800 MW), a-chymotrypsin (25,000 MW), hexose kinase (100,000 MW), and glucose oxidase (186,000 MW) were determined in order to calibrate the column. [Pg.66]

Tnterfacial phenomena play a fundamental role in biological systems. It A is important to know if surface energy and anisotropy affect the conformation of biological macromolecules. Well defined physicochemical models might simplify this problem (1- 8) spread monolayers at the air-water interface exemplify this kind of model. For polypeptides which are introduced as simple models of proteins, no surface denatura-tion of the spread macromolecules occurred (9, 10, 11). Protein structures are too complex to yield direct information about eventual changes of conformation, but one can detect the presence or the disappearance of biological activity—e.g., enzymic activity. The enzyme would be denatured if the conformation were modified by the anisotropy of the interface. [Pg.216]

It should be emphasized that, though we believe that we know the source of the A term, the causative mechanism has not been established unequivocally. Certainly, no quantitative theory is available (c.f. (7)). Therefore, the problem must be regarded as open. Nonetheless, the experimental procedures and the data themselves are extremely useful in investigations of water-protein and protein-protein interactions. [Pg.171]

A protein must be purified before its structure and the mechanism of its action can be studied. However, because proteins vary in size, charge, and water solubility, no single method can be used to Isolate all proteins. To Isolate one particular protein from the estimated 10,000 different proteins in a cell is a daunting task that requires methods both for separating proteins and for detecting the presence of specific proteins. [Pg.86]


See other pages where Water-protein NOEs is mentioned: [Pg.163]    [Pg.313]    [Pg.336]    [Pg.140]    [Pg.366]    [Pg.184]    [Pg.98]    [Pg.306]    [Pg.310]    [Pg.143]    [Pg.73]    [Pg.174]    [Pg.277]    [Pg.296]    [Pg.381]    [Pg.132]    [Pg.236]    [Pg.173]    [Pg.134]    [Pg.132]    [Pg.236]    [Pg.56]    [Pg.100]    [Pg.107]    [Pg.338]    [Pg.211]    [Pg.98]    [Pg.172]    [Pg.458]    [Pg.456]    [Pg.274]    [Pg.300]    [Pg.47]    [Pg.78]    [Pg.33]    [Pg.33]    [Pg.107]    [Pg.159]    [Pg.806]    [Pg.17]    [Pg.906]    [Pg.143]   
See also in sourсe #XX -- [ Pg.151 ]




SEARCH



Spin water-protein NOEs

Water proteins

© 2024 chempedia.info