Bonding non-covalent

The SUR-Kir6.2 complex is a non-covalently bonded octamer (4 x SUR/4 x Kir6.2), with the poreforming Kir6.2 channels located at the centre (Fig. 2). 

These early results have since been confirmed and extended by a vast and still growing body of research. All of the contemporary spectroscopic techniques (ir, uv, visible, nmr, esr) have been brought to bear on the problem, and further confirmation has come from cryoscopic and conductometric studies. The early confusion that resulted from the coexistence of both donor-acceptor or non-covalently-bonded complexes) has been clarified. This research has been extensively reviewed10,13-15 and will not be detailed here. 

Keywords. Antibodies, Biosensors, Non-covalent bond. Atomic force microscopy, Supramolecular chemistry... 

XB is a particularly directional interaction, more directional than HB. The angle between the covalent and non-covalent bonds around the halogen in D- X-Y is approximately 180° [48]. As discussed above, the origin of this directionality is in the anisotropic distribution of electron density around the halogen atom. Figure 5 shows the Cambridge Structure Database (CSD, ver-... 

It has been emphasized that in the construdion of complex molecular and supramolecular architectures the use of non-covalent bonding can be more efficient and more economic than the conventional covalent approach.1351 We outline here, how the interplay of a hydrogen bonding and alkyl chain... 

The 15-kDa J chain is synthesised by the same B-cell clone that produces the IgA molecule. The IgA molecules are transported across the epithelial cells and enter the lumen, this transport being mediated via another protein called the secretory chain (SC). The IgA molecules that are finally secreted are dimers of relative molecular mass of 400 kDa. The heavily glycosylated SC (80 kDa), synthesised and secreted by the epithelial cells, binds to the IgA molecules via non-covalent bonds. The IgA molecule thus has a valency of 4 (i.e. a single molecule has four antigen-binding sites), with all four sites recognising the same antigen. 

The extra absorbances observed by UV/VIS spectroscopy are due to equilibria which are quickly established after mixing, with the formation of non-covalent bonds and without (or before) reactions with covalent bond formations between the partners. The acidification of donor-acceptor mixtures, return the absorbance values of the spectrum to the values of the separate compounds. 

CNTs can conjugate with nucleic acids via non-covalent bond. ssDNA, short double-stranded DNA and total RNA molecules can attach to the surface of CNTs and can disperse CNTs in aqueous environment. The poly(30T) has the highest dispersion efficiency (Zheng et al., 2003). For example, 1 mg DNA molecules mix with lmg CNTs in 1ml water, yield at most 4mg/ml CNT solution. DNA-CNT complexes can be purified or isolated by electronic properties such as agarose gel electrophoresis and centrifuge method (Cui et al., 2004a Karajanagi et al., 2004). 

Functionalization of CNTs with Proteins via Covalent or Non-Covalent Bond... 

CNTs can be functionalized with protein via non-covalent bond (Li et al., 2005 Kim et al., 2003 Mitchell et al., 2002). For example, (beta-lactamase I, that can be immobilized inside or outside CNTs, doesn t change enzyme s activity (Vinuesa and Goodnow, 2002). Taq enzyme can attach to the outside of CNT, and doesn t change its activity (Cui et al., 2004). Peptide with Histidine and Tryptophan can have selective affinity for CNT(Guo et al., 1998). Monoclonal antibody can attach to SWNTs. Protein-modified CNTs can be used to improve its biocompatibility and biomolecular recognition capabilities (Um et al., 2006). For example, CNTs functionalized with PEG and Triton X-100 can prevent nonspecific binding of protein and CNTs. Biotin moiety is attached to the PEG chains Streptavidin can bind specifically with biotin-CNT (Shim et al., 2002). 

CNT can markedly reinforce polystyrene rod and epoxy thin film by forming CNT/polystyrene (PS) and CNT/epoxy composites (Wong et al., 2003). Molecular mechanics simulations and elasticity calculations clearly showed that, in the absence of chemical bonding between CNT and the matrix, the non-covalent bond interactions including electrostatic and van der Waals forces result in CNT-polymer interfacial shear stress (at OK) of about 138 and 186MPa, respectively, for CNT/ epoxy and CNT/PS, which are about an order of magnitude higher than microfiber-reinforced composites, the reason should attribute to intimate contact between the two solid phases at the molecular scale. Local non-uniformity of CNTs and mismatch of the coefficients of thermal expansions between CNT and polymer matrix may also promote the stress transfer between CNTs and polymer matrix. 

BoNTs (150 kDa) consist of two polypeptide chains the heavy chain (HC, 100 kDa) and the light chain (LC, 50 kDa), linked with disulfide and non-covalent bonds. The amine end of the LC is responsible for intraneural enzymatic activity. The HC contains a membrane translocation domain (a 50 kDa amino-terminal polypeptide) and a receptor-binding part (a 50 kDa carboxy-terminal polypeptide) (DasGupta, 1990 Krieglstein et ah, 1994). BoNT/A forms dimers, trimers, and bigger structures. BoNT/E generally has a monomer structure, but sometimes forms dimers. BoNT/B is a dimer (Ledoux et ah, 1994). 

Assemblies of macromolecules held together by non-covalent bonds are named by combination of the names of the constituent macromolecules together with an italicized connective between them. 

The Commission on Macromolecular Nomenclature is currently working on the extension of macromolecular nomenclature to branched and cyclic macromolecules, micronetworks and polymer networks, and to assemblies held together by non-covalent bonds or forces, such as polymer blends, interpenetrating networks and polymer complexes. 

Yoshida E, Kunugi S. Micelle formation of nonamphiphiUc diblock copolymers through non-covalent bond cross-linking. Macromolecules 2002 35 6665-6669. 

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