Low affinity binding

The differences between palytoxin and PDBu with respect to kinetics, temperature dependence, and effect on low affinity binding suggest that these two different types of tumor promoters may be acting through different mechanisms. Further, in contrast to PDBu, the effect of palytoxin is not readily reversible (33). To determine where the two pathways differ, we compared the relative ability of palytoxin and PDBu to inhibit EGF binding in protein kinase C depleted cells. Swiss 3T3 cells were depleted of protein kinase C to different extents by exposing confluent quiescent cells to 0, 20, 200, or 2000 nM PDBu for 72 hr. Previous results indicate that this treatment depletes cells of protein kinase C activity in a dose-dependent manner (31). 

Drug High-Affinity Binding Low-Affinity Binding... 

Figure 5.6 Biphasic concentration-response plot for an enzyme displaying a high- and low-affinity binding interaction with an inhibitor. In panel A, the data are fit to Equation (5.4) and the best fit suggests a Hill coefficient of about 0.46. In panel B, the data are fitted to an equation that accounts for two, nonidentical binding interactions Vj/v0 = (a/(l + ([/]/ICs0))) + ((1 - a)/(l+([t]/IC(o)))> where a is an amplitude term for the population with high binding affinity, reflected by IC , and IC 0 is the IC50 for the lower affinity interaction. (See Copeland, 2000, for further details.)...

Leukotriene B4 has been implicated in inflammatory processes and chemo-taxis. The G-protein-coupled receptor in human myeloid cells was postulated to possess two distinct binding sites. Photoaffinity studies using unmodified tritiated LTB4 as photoreactive species labeled two different proteins in the presence (53 kDa) and in the absence of a non-cleavable GTP analogue (56 kDa). This means that stabilization of the G-protein in the GTP-bound state resulted in an interconversion of the first high affinity binding site to an alternative low-affinity binding site [99]. 

Type XXIII collagen contains about 540 residues. The NCI domain contains a transmembrane sequence and is followed by COLl, NC2, COL2, NC3, COL3, and NC4 at the C-terminus. Furin proteinases may cleave the NCI domain, and the cleaved secreted portion of type XXIII collagen may also form multimers and display low-affinity binding to heparin in vitro ... 

While the amplification of the DCL by Con A was relatively weak, as expected for such a low affinity binding system, the system demonstrated the effectiveness of mild disulfide bond exchange when applied to DCC directed by a protein target. Lehn subsequently reported a second DCC investigation into the Con A binding site involving sugars linked... 

It is informative to compare the observed dissociation constant for the enkephalin-PS interaction with those reported for other systems. Methionine enkephalin has been shown ( ) to bind to brain membrane with a high affinity binding constant of 1.7 X IQ M and a low affinity binding constant of 1.7 x 10 ... 

Remove biotin from the low affinity binding sites by washing the column with... 

Some lower-affinity sites are associated with interactions of the C-termi-nal B(3 chain with the coiled-coil backbone (Everse et al, 1999 Kostelansky et al, 2002). Other low-affinity binding sites are less well defined. There is evidence that some of these sites may be associated with the sialic acid residues on the carbohydrate chains (Dang et al, 1989). 

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