End association

The observed molecular weight suggests that this polymer associates into a dimer in CHCI3, but that this aggregation is effectively blocked by small amounts of DMF. The particle lengths are not quite in the 2 1 ratio indicative of end-to-end association, but the increase in length is sufficiently large to make such a mechanism worthy of additional study. 

End-to-end association. The simplest model is one in which each association step has the same equilibrium constant K. This is equivalent to the familiar Flory most-probable polymerization scheme. Thus we write the recursion relations... 

Intramolecular chain end associates partly formed in the polymerization by bifunctional chains and Na as the counterion in THF... 

Fig. 3.3. Schematic illustration of the proposed architecture of mucus glycoproteins, (a) Subunits constitute a linear array of oligosaccharide clusters interspersed with naked stretches of protein. (b) Trypsin digestion affords glycopeptides corresponding to the oligosaccharide clusters. (c) The whole mucins are formed by an end-to-end association of subunits via disulphide bonds, (d) The hydrodynamic model of mucus glycoproteins conforms to a random coil within a spheroidal solvent domain. (After Allen et al., 1984.)...

Subunit 6 of the bovine bc complex consists of four helices and connecting loops. Located in the matrix, it contacts the exposed part of helix F, G, and H of cytochrome b of one monomer and core 1 and core 2 from the other monomer. It has been suggested this subunit is involved in quinone binding (Yu and Yu, 1982) and proton translocation (Cocco et al., 1991) but no supporting evidences has been observed in the crystal structures. Subunit 7 of the complex is anchored in the matrix side as its N-terminal end associates with the core 1 protein as part of a P-sheet its C-terminal 50 residues form a long, bent transmembrane helix (see Figure 3). 

Associations and aggregations can have cardinalities, indicating how many objects of one class can be associated with the same object of the other class. Each relationship may have two cardinaHties, one for each end. Typical cardinahties are 1 (each object at the other end must have exactly one object at this end associ-... 

On the other hand, those possessing two active end-groups, on both ends, associate with bivalent cations into cyclic aggregates. Their rings may open yielding a linear form, viz. 

The formation of junctional channels requires end-to-end association between the extracellular domains of hemichannels. This interaction is not likely to be covalent because junctional channels can be split into hemichannels by alkaline urea treatments (7, 79). However, the formation of junctional channels between mRNA-injected oocytes is critically dependent on the presence of the three cysteines in each connexin extracellular loop (78). These cysteines apparently do not form interhemichannel disulfide bonds (80-82), but may serve to stabilize the extracellular domains during the homophilic binding reaction with the apposing hemichannel. 

The kinetics of anionic polymerization of MMA is complicated by chain-end association effects and the... 

The kinetics of polymerization of cyclosiloxanes is complicated by chain-end association. Complexation of counterions with cryptands disrupts the aggregates. For the lithium [2.1.1] cryptand complex in aromatic solvent at... 

Pruyne D, Evangelista M, Yang C, Bi E, Zigmond S, et al (2002) Role of formins in actin assembly nucleation and barbed-end association. Science 297 612-615... 

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