Mechanism of Threading a Polymer Through a Macrocyclic Ring

Abstract

The translocation of biopolymers through pores and channels plays a fundamental role in numerous biological processes. We describe here the mechanism of the threading of a series of polymer chains through a synthetic macrocycle, which mimics these natural processes. The threading of polymers involves a kinetically favorable "entron" effect, which is associated with the initial filling of the cavity by the end of the polymer. A preassociation between the outside of the macrocycle and the polymer induces a process in which the polymer end loops back into the cavity of the macrocycle. This looping mechanism results in accelerated threading rates and unidirectional motion and is reminiscent of the protein translocation through membrane pores.

Effects of Alkali Metal Ion Cationization on Fragmentation Pathways of Triazole-Epothilone

“…Recently, chemical compounds with different macrocyclic rings inside themselves have attracted more interests in different research fields, including synthetic chemistry, natural products, and chemical biology [13][14][15][16][17][18][19][20][21]. For example, as one of the most attractive drugs for cancer therapy, epothilones and their relatives have evoked a vast research effort within academic and pharmaceutical research groups that include numerous total and partial syntheses and extensive structure-activity relationship studies [15][16][17][18][19][20][21].…”

Securing a Supramolecular Architecture by Tying a Stopper Knot

“…Finally, we demonstrated that the ring could thread over the about 10 nm length of the untangled strand22 and the rotaxane architecture subsequently be secured by tying the stopper knot (Scheme 1, steps (i) and (ii)). Addition of trifluoroacetic acid to a solution of DB24C8 (10 equiv) and L1 in CD 2 Cl 2 afforded the pseudorotaxane complex L1 H + over 48 h (Figures 3 a and S7).…”

The Frontiers of Organic Chemistry at the Bürgenstock Conference

“…This process causes accelerated unidirectional threading, which is reminiscent of translocation of proteins through membrane pores. [7] In the second part of his talk, he discussed single-molecule studies of enzymatic activity. It was postulated that enzymes are only active during a small fraction of time, and for the rest they are dormant, which is proposed to be related to structural dynamics and conformational changes.…”