The multivalent RGD peptides exhibited rather loose linkages partly including oligo(ethylene glycol) spacers (EG(n)) with different chain lengths. Therefore,
the dependence of multivalent ROD systems with and without EG(n) linkers were investigated on their binding properties to cultured alpha(v)beta(3) integrin-expressing U87MG cells.
Methods: We synthesized a series of di-, tri- and tetravalent rigid scaffolds (terephthalic acid, trimesic acid and adamantane-1,3,5,7-tetracarboxylic acid) conjugated to c(RGDyK) ligands, which were linked contiguously GSK1838705A or separated by the oligo(ethylene glycol) spacers. The inhibition constants of these c(RGDyK) derivatives were determined by competition assays
with (125)I-labeled echistatin.
Results: While c(RGDyK) function is a relative weak competitor against [(125)I]echistatin (Ki, 329 +/- 18 nM) for alpha(v)beta(3) integrin-expressing U87MG cells, RGD dimers improved the competition potency considerably (K 64 23 nM). This effect was even more pronounced with the ROD trimers (K1, 40 +/- 7 nM) and tetramers (K1, check details 26 +/- 9 nM). The introduction of EG(n) spacers and the increase of linker lengths proved to be detrimental since more competitors were needed to compete with [1251]echistatin. The EG(6) group, for example, reduced the inhibition constants by 29% (dimer), 57% (trimer) and 97% (tetramer).
Conclusion: The binding experiments performed with the three forms of multivalent ROD ligands indicate the weakening of competitive potency against [(125)I]echistatin with the introduction of EG(n) spacers. This effect may be related to the decrease of the effective ROD molarity, which becomes most prominent within the tetravalent series. (C) 2010 Elsevier Inc. All rights reserved.”
“In intracellular calcium signaling, calcium buffers has been recognized for their role in reshaping and localizing the calcium concentration profile in the vicinity of the channel, as well as reducing the effective diffusion of free calcium. In
the presence of an excess of endogenous or exogenous buffers, linearization of the reaction-diffusion system describing the calcium-buffer dynamics has C1GALT1 been instrumental in understanding the extent of the microdomain formation and in quantifying the apparent diffusion of the free calcium. In these linearized models, the conclusions are usually drawn from the steady-state solutions upon the opening of the channel. In this work, using the joint Laplace-Fourier method, we give an explicit integral transient solution, as well as, the long-time asymptotic behavior of the linearized calcium-buffer dynamics. The results confirm and emphasize the long stated intuitions on the diffusive character of the calcium-buffer dynamics. Numerical validations of our analytical results will be discussed. (C) 2010 Elsevier Ltd. All rights reserved.