抄録
Understanding the detailed reaction mechanism of cellulases is indispensable in designing its artificial mutants with both higher activity and higher stability than those of natural cellulases. Many oligo-cellulose analogues with tolerance against cellulases have been developed as inhibitors and provided stable complexes with cellulases. However, it is difficult to insert the substrate mimics in the reaction site (the -1 subsite) in a desirable form, because the enzymes force the pyranose ring at that site to become distorted. Since we supposed that replacement of the pyranose ring with cyclohexene ring would reproduce the half-chair conformation, the expected transition state structure, without distortion, cellulose analogues 1 and 2 would be ideal for the inhibitor of the cellulases. Thus, we performed the syntheses of these analogues in the present study. Differential scanning calorimetric experiments revealed that these molecules were inert against NCE5 isolated from Humicola insolens and that the cyclohexene ring thus introduced effected for the stabilization of the cellulase- analogue complex. Cellotetraose analogue 2 was most effective among the compound we synthesized in these studies to show the Ki value 1.6 μM against NCE5. We will also report the synthesis compound 23 which was designed with our assumption that the most stable conformation of this molecule will fit cellulase without distortion. It was found that 23 exhibited anti-feedant and toxicity against termites.
