Zipper concept

The outlined zipper concept does indeed work, on condition that the C14 ester is omitted (Scheme 8) [14]. Treating a such simplified precursor as 28 with guanidine and then HCl gave racemic pentacyclic guanidine 29, in one step and in 20 % yield, as its tetrafluoroborate salt, which could be characterized by X-ray analysis. 

In the argument against the ECbECN concept, much, perhaps too much, store has been placed by critics on observations which seem to undermine the zipper mechanism in the apparent belief that this mechanism is axiomatic with the ECbECN as a whole. However, as has been shown, changing physico-chemical properties of progressively fluorinated products inevitably result in different adsorptive forces for these compounds, with possible desorption from the electrode as a consequence this situation could apply equally well with products formed via a carbocation mechanism as with radically generated compounds, even though, as originally stated, the implication is otherwise. 

This concept of intermolecular association likewise explains the reverse action of retrogradation, zippering together linear molecules to give gels or insoluble precipitates (Figure 9). If the action proceeds slowly as in a 1% starch indicator... 

Banta and co-workers have introduced a series of functional protein domains into ACiqA hydrogels.In a proof-of-concept, fluorescent protein domains (either red fluorescent protein (RFP) or green fluorescent protein (GFP)) were fused to ACiqA proteins between the disordered Cio domain and one of the leucine zipper domains to make an asymmetrical tetrablock protein polymer. These fusion proteins readily assembled into hydrogels and are more stable than (i.e., do not erode as quickly as) the related ACjqA hydrogels. The increased stability may be due to the asymmetry of the fusion proteins, which... 

Fig. 3 Concept of 02 quenching/scavenging and activation for (A) Enzyme activatable PS (B) Zipper molecular beacon.

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