Gradient dependencies

Chemokines, a superfamily of small (8 to 14 kd) chemoattractant cytokines, were originally identified by their capacity to mediate gradient-dependent cell migration, accompanied by Ca2+ flux, in vitro. Sequence homology of mammal, bird, and fish chemokines indicates that this family of proteins is highly conserved throughout evolution. Chemokines are multifunctional molecules with a vast repertoire of specialized functions in different organs. Broadly, chemokine actions are associated with cell adhesion, cytokine secretion, cellular... 

Inui, K., Saito, H. and Hori, R. (1985). H+ gradient-dependent active transport of tetaethyl-ammonium cation in apical-membrane vesicles isolated from kidney epithelial cell line LLC-PK Biochem. J. 227 199-203. 

Volatile amines from Ci to C(, and ammonia were separated on a PoraPLOT column, with or without a temperature gradient, depending on volatility. The method is applicable to determination of the purity of manufactured amines. Trace analysis of these amines can be performed by capillary GC-FID and of ammonia by GC-ELCD101. 

The form of the above equations suggests that the only properties of the bed on which the pressure gradient depends are its specific surface S (or particle size d) and its voidage e. However, the structure of the bed depends additionally on the particle size distribution, the particle shape and the way in which the bed has been formed in addition both the walls of the container and the nature of the bed support can considerably affect the way the particles pack. It would be expected, therefore, that experimentally determined values of pressure gradient would show a considerable scatter relative to the values predicted by the equations. The importance of some of these factors is discussed in the next section. 

H. Nakamura, F. Ushigome, N. Koyabu, S. Satoh, K. Tsukimori, H. Nakano, H. Ohtani, and Y. Sawada. Proton gradient-dependent transport of valproic acid in human placental brush-border membrane vesicles. Pharm Res. 19 154—161 (2002). 

Said, H.M., Redha, R., and Nylander, W., A carrier-mediated Na+ gradient-dependent transport for biotin in brush-border membrane vesicles, Am. ]. Physiol., 253, G631, 1987. 

The peak capacity of a gradient depends on the gradient operating conditions. This is discussed in detail in Reference 9. Here we will just give the relevant equation for gradients over a broad range of solvent composition without going into further detail ... 

In first-order reactions, the concentration gradient depends on the local concentration at time t ... 

The pressure curves for both laminates (Fig. 10.8) showed the existence of a horizontal pressure gradient and that the magnitude of the gradient depends on the amount of horizontal flow (i.e., the larger gap distance between the laminate edges and the dams resulted in more horizontal flow). 

Fig. 16. Decomposition of gradient-dependent phosphoprotein induced by the addition of the calcium ionophore X 537 A and ADP195. Native vesicles were loaded with calcium phosphate at 23 °C. After addition of EGTA final concentration 10 mM, the phosphoprotein ( ) level rises in a few seconds to a maximum and then slowly declines. On addition of 40 pM ionophore X 537 A (I), phosphoprotein...

Properties Gradient independent phosphoprotein Gradient dependent phosphoprotein... 

Gradient-Dependent Phosphoprotein Formation. Properties of gradient-dependent phosphoprotein are more complicate to study than those of the gradient-independent phosphoprotein species. In order to obtain a maximum yield of gradient-dependent phosphoprotein of v 3 nmol/mg, it is important to accomplish that as... 

Fig. 19. Dependence of phosphoprotein formation in the presence and the absence of a calcium gradient on the concentration of phosphate195. Native vesicles were loaded with calcium phosphate at 23 °C in the presence of different phosphate concentrations. Formation of phosphoprotein was started by the addition of EGTA at a final concentration of 10 mM. The reaction was quenched after one minute when gradient-dependent phosphoprotein has reached an optimal value. The formation of phosphoprotein at 10 °C was started by EGTA addition after the assay was cooled. During the cooling period the vesicles do not lose any calcium, even if the assay is kept cool for more than 5. Gradient-dependent phosphoprotein...

C ----A 10 °C. Inset scatchard plot for gradient-dependent phosphoprotein... 

A more conclusive kinetic analysis is not only made difficult because of the temperature-dependent occurrence of different phosphoprotein species, but also by the fact that the spontaneous decay of gradient-independent as well as of gradient-dependent phosphoprotein depends on the concentration of phosphate. This phosphate dependence is not taken into account by the tentative reaction scheme. 

If the density gradient depends only on temperature and not on dissolved chemicals, N can be written as ... 

Peterlin,A, Gradient dependence of intrinsic viscosity of freely flexible linear macromolecules. J. Chem. Phys. 33,1799-1802 (1960). 

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