Protein molar concentration

Testing was done at 75 jjM compound and protein concentration. The ratio between compound and protein molar concentration was 1 1. 

FIGURE 5.10 Effects of co-expressed G-protein (G ) on neuropeptide NPY4 receptor responses (NPY-4). (a) Dose-response curves for NPY-4. Ordinates Xenopus laevis melanophore responses (increases light transmission). Ordinates logarithms of molar concentrations of neuropeptide Y peptide agonist PYY. Curves obtained after no co-transfection (labeled 0 jig) and co-transfection with cDNA for Gai6. Numbers next to the curves indicate jig of cDNA of Ga]g used for co-transfection, (b) Maximal response to neuropeptide Y (filled circles) and constitutive activity (open circles) as a function of pg cDNA of co-transfected G g. 

Bmax, a term denoting the maximal binding capacity of an experimental binding system, usually a preparation containing receptors (membranes, cells). The magnitude is most often expressed in number of receptors per cell or molar concentration of receptors per milligram protein. 

P]0 is the total molar concentration of the protein and [L]0 is the total molar concentration of ligand. X is the molar concentration of the bound species determined according to the chemical shift change ... 

It has often been questioned whether the rates and kinetics of purified enzymes, determined in very dilute solutions with high concentrations of their substrates, but not always of their cofactors, can be extrapolated to the conditions prevailing in the matrix. Much of the mitochondrial water will be bound to protein by hydrogen bonds and electrostatically, but there is also a pool of free water which may only be a fraction of the total water (Gitomer, 1987). The molar concentrations of intermediates of the citrate cycle and of p-oxidation are very low, usually less than those of most enzymes (Srere, 1987 Watmough et al., 1989 Sumegi et al., 1991). The extent to which cofactors and intermediates bind specifically or nonspecifically to enzymes is not known. It is therefore difficult to estimate concentration of these... 

Methylanaline could be transnitrosated with nitrite and S-nitrosocysteine and also by a simulated protein bound nitrite. In the latter case, an important factor was the local concentration of nitrosothiol groups on the matrix. The effects of S-nitrosocysteine as an inhibitor of lipid oxidation, as a color developer, and as an anticlostridial, have been reported recently in a turkey product (31). The Molar concentration of RSNO equating to 25 ppm nitrite gave similar results for color and inhibition of lipid oxidation but had less anti-clostridial activity. Transnitrosation between RSNO and heme protein was demonstrated. 

A technique utilizing genetically modified bacteria to report the presence of particular compounds in soil has also been developed (37). These bacteria respond to the presence of specific compounds in their environment by producing ice-nucleation proteins that enter into cell membranes, enabling cells to be detected by means of a droplet freezing assay. The presence of trytophan in 1-10 i molar concentrations has been detected using reporter bacteria in a study examining loss of amino acids from roots of Avena barbata into soil (38). 

It has been demonstrated that extremely tight control is exhibited over the intracellular zinc concentrations by the metalloregulatory proteins controlling zinc homeostasis. It had previously been thought that intracellular zinc was available in a pool of free zinc ions in the micro- to pico-molar concentration. An important study shows that these concentrations of free zinc are inconsistent with the concentrations required to trigger zinc uptake.974... 

It has been found that silver ions catalyze the thiolation process with proteins, allowing the reaction to be completed rapidly at physiological pH (Benesch and Benesch, 1958). The addition of an equal molar concentration of AgNO j forms an insoluble complex with the thiolactone, and this in turn reacts with protein amines. 

Measure the absorbance of the biotinylated protein solution at 354 nm. Use the molar extinction coefficient for the chromogenic group (e = 29,000 M-1cm-1) to determine the concentration of biotin present. To determine the molar ratio of biotin-to-protein, divide the molar concentration of biotin by the molar concentration of protein present (which may be determined by using the Coomassie assay or the BCA assay methods). 

Since the second complex contains two molecules of drug, therefore, we refer to it as dimer complex. Keeping in view the milli molar concentration of the metal ion present in the cell, possibility of the formation of dimer complex is more under in vivo conditions. However, in certain cases of cancer the metal ion concentration goes down to micro molar range. Under these unusual conditions, complex I is formed. Recently we have shown that mithramycin forms only dimer complex with Zn +, another metal ion playing an important role as cofactor in many enzymes and DNA binding proteins like transcription factors. 

Fiq. 1. Reciprocal plot the binding of [ Clwarfarin to human albumin, r moles of warfarin bound per mole of protein [D] molar concentration of unbound warfarin. After Solomon and Schrogie (S22), reproduced by courtesy of Microforms International Marketing Corporation. 

Concentration of a sample in a SpeedVac, a centrifuge with open rotor running in vacuum, is not lyophilization because the sample is not frozen therefore, this method does not fit for macromolecules with defined structures. The reconstitution (dissolving) of protein samples concentrated in a SpeedVac is often more difficult and comparable to drying with air. But it is the method of choice for concentration of solutions of low-molar mass substances, e.g., peptides, since the sample is collected at the bottom of the tube by means of centrifugal force. 

For evaluation of efficiency of medical sorbents, the issue of their deliganding properties, i.e. an ability to withdraw toxic protein bound compounds (ligands) is of great importance. If a sorbent possesses strong deliganding capability as, for example, some types of modem carbon hemosorbents do [11,12], then after contact with such an adsorbent, the ratio of molar concentrations of ligand - protein carrier (M /Mp) decreases, i.e. the transport protein transforms into a more purified state than it was initially (Table 21.3). 

Intracellular Concentration of Enzymes To approximate the actual concentration of enzymes in a bacterial cell, assume that the cell contains equal concentrations of 1,000 different enzymes in solution in the cytosol and that each protein has a molecular weight of 100,000. Assume also that the bacterial cell is a cylinder (diameter 1.0 /xm, height 2.0 /rm), that the cytosol (specific gravity 1.20) is 20% soluble protein by weight, and that the soluble protein consists entirely of enzymes. Calculate the average molar concentration of each enzyme in this hypothetical cell. 

What are the molar concentrations of the electron carriers in mitochondrial membranes In one experiment, cytochrome b was found in rat liver mitochondria to the extent of 0.28 pmol/g of protein. If we take a total mitochondrion as about 22% protein, the average concentration of the cytochrome would be 0.06 mM. Since all the cytochromes are concentrated in the inner membranes, which may account for 10% or less of the volume of the mitochondrion, the concentration of cytochromes may approach 1 mM in these membranes. This is sufficient to ensure rapid reactions with substrates. 

Recently, considerable progress has been made on the calculation of electrostatic and hydrophobic interactions in biochemical systems 189 19 >. We can expect such calculations to become common for protein-solid surface interactions. Thus we can expect approximate values for the adsorption energy in selected systems to appear in the near future. The problem of time-dependent conformational adaptation of the protein to the surface (and vice versa) will be much more difficult. Initially, we will have to resort to crude measures of the structural stability of a protein, such as the temperature at which thermal denaturation occurs, the urea molar concentration for solution denaturation, etc. One or more of the models given in Fig. 13 should apply. 

What factors can be used to predetermine the quality and utility of a method An analyst must consider the following questions Do I need a proximate analytical method that will determine all the protein, or carbohydrate, or lipid, or nucleic acid in a biological material Or do I need to determine one specific chemical compound among the thousands of compounds found in a food Do I need to determine one or more physical properties of a food How do I obtain a representative sample What size sample should I collect How do I store my samples until analysis What is the precision (reproducibility) and accuracy of the method or what other compounds and conditions could interfere with the analysis How do I determine whether the results are correct, as well as the precision and accuracy of a method How do I know that my standard curves are correct What blanks, controls and internal standards must be used How do I convert instrumental values (such as absorbance) to molar concentrations How many times should I repeat the analysis And how do I report my results with appropriate standard deviation and to the correct number of significant digits Is a rate of change method (i.e., velocity as in enzymatic assays) or a static method (independent of time) needed ... 

At low salt concentrations, the protein is unfolded because the hydrophobic interaction in these conditions is not sufficient to stabilize the folded structure. In molar concentrations of strongly salting-out potassium phosphate, however, the hydrophobic interaction is sufficient to stabilize the folded protein at very high concentrations of this salt, it forms crystals (Harel et al., 1988). The hydration of AMDH in potassium phosphate is similar to that of a nonhalophilic protein. Zaccai et al. (1989) suggested, therefore, that AMDH at low... 

When the taurine chloramine uptake rate exceeds the rate of NADPH-dependent regeneration of GSH, there is a net loss of cellular GSH level, causing protein-thiol oxidation, ATP loss, and disruption of cellular metabolism. Heme moieties are the other target of chloramine attack on cellular constituents. Oxidation of hemoglobin to methemoglobin (and other hemoproteins to their oxidized derivatives) occurs at 10-fold excess of chloramine taurine molar concentration compared... 

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