Proteins curves

Figure 15.9 The results of capture ELISA on native RNase A and formalin-treated RNase A. Right panel, native RNase A (curve 1) and unfractionated formalin-treated RNase A (curve 2). Left panel, individual fractions of formalin-treated RNase A monomer (curve 3), dimmer (curve 4), trimer (curve 5), tetramer (curve 6), and a mixture of oligomers with >5 cross-linked proteins (curve 7). The ELISA plate wells were coated with monoclonal antibody against bovine pancreatic RNase A (1 pg/mL) overnight at 4°C and then blocked with bovine serum albumin. The wells were incubated for lh at 37°C in the presence of various concentrations of antigen in lOOpL of PBS. After washing, each plate well received a 1 4000 dilution of horseradish peroxidase conjugated rabbit polyclonal anti-RNase A antibody followed by incubation at ambient temperature for lh. After washing, detection was achieved using a mixture of 2,2,-azino-di-(3-ethylbenzthiazoline-6-sulphonate) and hydrogen peroxide. Absorbance was monitored at 405 nm. See Rait etal.11 for details.

Figure I. Effect of heating of soy milk before drying and effect of addition of N-ethylmaleimide (NEMI) to heated soy milk on the insolubilization of protein after drying. The curves are (a), dried without adding NEMI (b), dried after adding SEMI and (C), the values of (a) minus the values of (b). Curve (a) indicates total amount of insolubilized protein curve (b) indicates the amount of protein insolubilized by mechanisms other than by intermolecular disulfide bond formation and curve (c) indicates the amount of protein insolubilized through disulfide bond polymerization (3).

Such a clear separation of two proteins will not always be obtained. To go to the other extreme, Fig. 8c and d shows the corresponding curves for a solution containing serum albumin and pseudoglobulin, each at 30 gm per liter. The precipitation peaks occur at the same salt concentration, and therefore the residual protein curve shows a single smooth step. 

Adzuki protein showed a broad endothermic peak at 79 °C (curve II). The effect of protein on the gelatinization of starch was not significant because a heating DSC curve of the mixture of starch and protein with the same mixing ratio as in adzuki beans, i.e. 40% protein (curve I), showed a similar endothermic peak to that of isolated starch alone (not shown), and the enthalpy per gram of starch did not change on addition of protein. 

Fig. 1. The concentration of human serum albumin adsorbed to hydroxyapatite particles versus bulk protein concentration along several concentration trajectories. Curve A a gradual increase in bulk protein concentration via flow of 0.066 g/L protein solution into chamber of particles. Curve B a gradual decrease in bulk protein concentration via flow of buffer solution without protein. Curve C a protein concentration of 0.695 g/L for 30 min followed by a gradual decrease in bulk protein concentration via flow of buffer solution. Curve D a protein concentration of 0.858 g/L for 8 h followed by a gradual decrease in bulk protein concentration via flow of buffer solution. Curve I Protein concentrations corresponding to the horizontal axis for 8 h. Taken with permission from Ref 77.

The time course of HPOD formation was examined with nonlinear regression analysis over a 6 h period at 15°C using IMM-LOX that contained 3.0 mg protein. Curve fit estimates were obtained using Equation 1,... 

Fig. 7.7. Examples of CD spectra of all-a proteins. Curves 1, myoglobin 2, parvalbumin 3, cytochrome c.

Protems can be physisorbed or covalently attached to mica. Another method is to innnobilise and orient them by specific binding to receptor-fiinctionalized planar lipid bilayers supported on the mica sheets [15]. These surfaces are then brought into contact in an aqueous electrolyte solution, while the pH and the ionic strength are varied. Corresponding variations in the force-versus-distance curve allow conclusions about protein confomiation and interaction to be drawn [99]. The local electrostatic potential of protein-covered surfaces can hence be detemiined with an accuracy of 5 mV. 

A typical force curve showing the specific avidin-biotin interaction is depicted in figure Bl.20.10. The SFA revealed the strong influence of hydration forces and membrane undulation forces on the specific binding of proteins to membrane-bound receptors [81]. 

Figure Bl.20.10. Typical force curve for a streptavidin surface interacting with a biotin surface in an aqueous electrolyte of controlled pH. This result demonstrates the power of specific protein interactions. Reproduced with pennission from [81].

Schulten, K. Curve crossing in a protein coupling of the elementary quantum process to motions of the protein. In Quantum mechanical simulation methods for studying biological systems, D. Bicout and M. Field, eds. Springer, Berlin (1996) 85-118. 

Fig. 1. Exit route of xenon in simulations of the extraction process. The xenon atom is solid black. The atoms of the residues surrounding the exit path are shown a.s spheres, and the protein backbone is shown as a thin curve. On the left, the xenon is viewed through the exit between residues on the right, the view is from (ho side and the direction of the tug is marked with a line.

Tanford, C., Kirkwood, J. G. Theory of protein titration curves. I. General equations for impenetrable spheres. J. Am. Chem. Soc. 79 (1957) 5333-5339. 6. Garrett, A. J. M., Poladian, L. Refined derivation, exact solutions, and singular limits of the Poisson-Boltzmann equation. Ann. Phys. 188 (1988) 386-435. Sharp, K. A., Honig, B. Electrostatic interactions in macromolecules. Theory and applications. Ann. Rev. Biophys. Chem. 19 (1990) 301-332. 

Bashford, D., Karplus, M. Multiple-site titration curves of proteins an analysis of exact and approximate methods for their calculation. J. Phys. Chem. 95 (1991) 9556-9561. 

Tanford, C., Roxby, R. Interpretation of protein titration curves Application to lysozyme. Biochem. 11 (1972) 2192-2198. 

Fig. 10. Selectivity curves A—D for Sephadex G-75, G-lOO, G-150, and G-200, respectively, for globular proteins.

When water activity is low, foods behave more like mbbery polymers than crystalline stmctures having defined domains of carbohydrates, Hpids, or proteins. Water may be trapped in these mbbery stmctures and be more or less active than predicted from equiUbrium measurements. As foods change temperature the mobiUty of the water may change. A plot of chemical activity vs temperature yields a curve having distinct discontinuities indicating phase... 

Dmg distribution into tissue reservoirs depends on the physicochemical properties of the dmg. Tissue reservoirs include fat, bone, and the principal body organs. Access of dmgs to these reservoirs depends on partition coefficient, charge or degree of ionization at physiological pH, and extent of protein binding. Thus, lipophilic molecules accumulate in fat reservoirs and this accumulation can alter considerably both the duration and the concentration—response curves of dmg action. Some dmgs may accumulate selectively in defined tissues, for example, the tetracycline antibiotics in bone (see Antibiotics,tetracyclines). 

A critical component of the G-protein effector cascade is the hydrolysis of GTP by the activated a-subunit (GTPase). This provides not only a component of the amplification process of the G-protein cascade (63) but also serves to provide further measures of dmg efficacy. Additionally, the scheme of Figure 10 indicates that the coupling process also depends on the stoichiometry of receptors and G-proteins. A reduction in receptor number should diminish the efficacy of coupling and thus reduce dmg efficacy. This is seen in Figure 11, which indicates that the abiUty of the muscarinic dmg carbachol [51 -83-2] to inhibit cAMP formation and to stimulate inositol triphosphate, IP, formation yields different dose—response curves, and that after receptor removal by irreversible alkylation, carbachol becomes a partial agonist (68). 

To quantitate proteins from staining, a densitometer aided by computer software is used to evaluate band areas of samples compared to band areas of a standard curve. Amido black, Coomassie Brilliant Blue, and silver stains are all appHcable for use in quantification of proteins. 

Fig. 15. En2ymatic hydrolysis of wheat gluten at 72.5°C and pH 7.5 by an alkaline protease from Bacillus licheniformis. The numbers on the curves are en2yme—substrate ratios (E/S) in activity units (AU)/kg of protein where S = 7.4% (N x 5.7).

The preliminary precipitation of proteins from milk is realized through the addition of solutions of acetic acid (1,7 mol/1) and sodium acetate (lmol/1) at t = 40-45°C before chromatographic isolation of OxTC. The precipitated proteins are separated by filtration. OxTC is detenuined in filtrate after its isolation on chromatographic column. Contents of OxTC was determined on calibration curve which is linear within concentration range 0,01-1,0 p.g/ml. 

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