A series of bulky carboxylates was introduced as a counteranion for N-methylpyrrolidinum salt end groups of poly(tetrahydrofuran), poly(THF), having molecular weights of ca. 5000. 4-(7,7,7-Triphenylheptoxy)benzoate was found to remain intact as a counteranion at ambient temperature but to cause the ring-opening reaction of pyrrolidinium groups at 90 °C to produce poly(THF) with bulky stopper groups in a pure form in 71% yield. The relevant ring-opening reaction also took place in the presence of such macrocyclics as 30-crown-10 and cyclodextrins, but an effective entrapping of cyclic components in polyrotaxanes was not achieved presumably because of the entropic repulsion between the two components.

Purified recombinant sorbose dehydrogenase from Sinorhizobium sp. 97507 exhibited high reactivity for 1,5-anhydro-d-glucitol (1,5-AG) and l-sorbose, but little activity for the other sugars or sugar alcohols tested. Kinetic analysis revealed that its catalytic efficiency (kcat/Km) for l-sorbose and 1,5-AG is 1.8 × 102 and 1.5 × 102 s−1·M−1, respectively.