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Binding Capability (binding + capability)
Selected AbstractsHigh Rate Silicification of Peptide-Polymer Assemblies Toward Composite NanotapesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 5 2008Stefanie Kessel Abstract Well-defined silica composite nanofibers are generated in a silicification process of self-assembled poly(ethylene oxide)-peptide nanotapes. Inspired by biological silica morphogenesis processes the nanotapes exhibit strong binding capabilities for silicic acid. Thus, pre-hydrolyzed tetramethoxysilane could be used as silica precursor. Very low concentrations (270 µM) and short contact times (10 s) are sufficient to form effectively integrated nano-composite tapes. [source] Cobalt(II) salen complex with two aza-crown pendants and its analogues as synthetic oxygen carriersCHINESE JOURNAL OF CHEMISTRY, Issue 6 2004Xing-Yue Wei Abstract Salen with two aza-crown ether pendants H2L1 and its analogues H2L2- H2L4 were successfully synthesized starting from benzo-10-aza-15crown-5 (BN15C5) or morpholine. Their structures were characterized by IR, MS, 1H NMR and elemental analysis, and were confirmed by X-ray diffraction analysis of H2L1. Moreover, the saturated oxygen uptake of their cobalt(II) complexes CoL1- CoL4 in diethyleneglycol dimethyl ether was determined at different temperature. The oxygenation contants (KO2 ) and thermodynamic parameters (,H° and ,S°) were calculated. The modulation of O2 -binding capabilities by pendant substituents were investigated as compared with the parent Schiff base complex CoL5 (CoSalen). The results indicate that the dioxygen affinities of CoL have been much more enhanced by aza-crown pendants than that by morpholino pendants, and the O2 -binding capabilities of CoL1 and CoL2 with aza-crown pendants would also be enhanced by adding alkali metal cations. [source] Alanine screening of the intracellular loops of the human bradykinin B2 receptor , effects on receptor maintenance, G protein activation and internalizationFEBS JOURNAL, Issue 13 2009Alexander Faussner The bradykinin B2 receptor is coupled to G protein Gq/11 and becomes sequestered into intracellular compartments after activation. To more closely define the receptor sequences involved in these processes and their functions, we systematically mutated all three intracellular loops (ICLs), either as point mutations or in groups of three to five amino acids to Ala, obtaining a total of 14 mutants. All constructs were stably expressed in HEK 293 cells and, with the exception of triple mutant DRY , AAA, retained the ability to specifically bind [3H]bradykinin. The binding affinities at 4 or 37 °C of several mutants differed considerably from those determined for the wild-type receptor, indicating an allosteric connection between the conformation of the binding site and that of the ICLs. Mutations in ICL-1 strongly reduced surface expression without affecting G protein signaling or [3H]bradykinin internalization. Two cluster mutants in the middle of ICL-2 containing basic residues displayed considerably reduced potencies, whereas two mutations in ICL-3 resulted in receptor conformations that were considered to be semi-active, based on the observation that they responded with phosphoinositide hydrolysis to compounds normally considered to be antagonists. This, and the fact that a cluster mutant at the C-terminal end of ICL-3 was signaling incompetent, hint at the involvement of ICL-2 and ICL-3 in Gq/11 activation, albeit with different functions. None of the mutants displayed reduced ligand-induced receptor internalization, indicating that the loops are not essential for this process. No conclusion could be drawn, however, with regard to the role of the DRY sequence, as the corresponding triplet mutation lacked binding capability. [source] Two subpopulations of thrombin-activated platelets differ in their binding of the components of the intrinsic factor X-activating complexJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 11 2005M. A. PANTELEEV Summary., Binding of fluorescein-labeled coagulation factors IXa, VIII, X, and allophycocyanin-labeled annexin V to thrombin-activated platelets was studied using flow cytometry. Upon activation, two platelet subpopulations were detected, which differed by 1,2 orders of magnitude in the binding of the coagulation factors and by 2,3 orders of magnitude in the binding of annexin V. The percentage of the high-binding platelets increased dose dependently of thrombin concentration. At 100 nm of thrombin, platelets with elevated binding capability constituted ,4% of total platelets and were responsible for the binding of ,50% of the total bound factor. Binding of factors to the high-binding subpopulation was calcium-dependent and specific as evidenced by experiments in the presence of excess unlabeled factor. The percentage of the high-binding platelets was not affected by echistatin, a potent aggregation inhibitor, confirming that the high-binding platelets were not platelet aggregates. Despite the difference in the coagulation factors binding, the subpopulations were indistinguishable by the expression of general platelet marker CD42b and activation markers PAC1 (an epitope of glycoprotein IIb/IIIa) and CD62P (P-selectin). Dual-labeling binding studies involving coagulation factors (IXa, VIII, or X) and annexin V demonstrated that the high-binding platelet subpopulation was identical for all coagulation factors and for annexin V. The high-binding subpopulation had lower mean forward and side scatters compared with the low-binding subpopulation (,80% and ,60%, respectively). In its turn, the high-binding subpopulation was not homogeneous and included two subpopulations with different scatter values. We conclude that activation by thrombin induces the formation of two distinct subpopulations of platelets different in their binding of the components of the intrinsic fX-activating complex, which may have certain physiological or pathological significance. [source] Impact of heterodimerization on intracellular localization of the ecdysteroid receptor (EcR)ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 1 2008Claudia Nieva Abstract Initially, nuclear import of the ecdysteroid receptor (EcR) in vertebrate cells (CHO-K1 and COS-7) does not afford a heterodimerization partner. Later on, EcR is retained in the nucleus only in the presence of a heterodimerization partner. Ultraspiracle (Usp) is more efficient compared to its vertebrate orthologue RXR and leads to an exclusively nuclear localization of EcR even in the absence of ligand. The DNA binding domain of the heterodimerization partner is important for retainment of EcR in the nucleus as shown by Usp4 (UspR130C), which has lost its DNA binding capability. The C-terminal end of Usp (Usp,205-508) encompassing the C-terminal part of the D-domain and the E- and F-domains are essential for retainment of EcR in the nucleus. Nuclear localization is further influenced by cell-specific factors, since hormone and heterodimerization stabilizes the EcR protein in a cell-specific way. Arch. Insect Biochem. Physiol. 2008. © 2008 Wiley-Liss, Inc. [source] Expression and Purification of Functional Human ,-1-Antitrypsin from Cultured Plant CellsBIOTECHNOLOGY PROGRESS, Issue 1 2001Jianmin Huang Human ,-1-antitrypsin (AAT), the most abundant protease inhibitor found in the blood, was expressed in rice embryonic tissue suspension cell culture. This was accomplished by cloning the codon-optimized AAT gene into a vector containing the rice RAmy3D promoter and its signal sequence. The synthetic gene incorporates codons synonymous with those found in highly expressed rice genes. Approximately 1000 stable transformed calli were produced by particle bombardment mediated transformation and were screened for high AAT expression using a porcine elastase inhibitory activity assay. The band shift assay also confirmed that rice-derived AAT is functional regarding its binding capability to the elastase substrate. Time course studies were conducted to determine the optimum, postinduction expression levels from cell culture. AAT expression equivalent to 20% of the total secreted proteins was achieved, and a purification scheme was developed that yielded active AAT with purity greater than 95%. The potential applications of purified plant-derived AAT for treatments of various AAT-deficient diseases are discussed. [source] | ||||||||||